diff --git a/R/AddProbDup.R b/R/AddProbDup.R
index b4928ad..9a0c214 100644
--- a/R/AddProbDup.R
+++ b/R/AddProbDup.R
@@ -44,6 +44,16 @@
 #' @return A data frame of the PGR passport database with the probable duplicate
 #'   sets fields added.
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #' 
 #' #' # Load PGR passport database
@@ -87,6 +97,12 @@
 #' GNwithdup <-  AddProbDup(pdup = GNdup, db = GN1000, addto = "I")                  
 #' 
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso \code{\link[PGRdup]{DataClean}}, \code{\link[PGRdup]{KWIC}},
 #'   \code{\link[PGRdup]{ProbDup}}
 #' @note When any primary ID/key records in the fuzzy, phonetic or semantic 
diff --git a/R/DisProbDup.R b/R/DisProbDup.R
index 2fccae8..5ffd61e 100644
--- a/R/DisProbDup.R
+++ b/R/DisProbDup.R
@@ -43,6 +43,16 @@
 #'   disjoint duplicate sets as an additional element \code{DisjointDupicates}
 #'   according to the choice specified in the argument \code{combine}.
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #'
 #' # Load PGR passport database
@@ -92,6 +102,12 @@
 #' lapply(disGNdup2, nrow)
 #'
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso \code{\link[PGRdup]{ProbDup}}
 #' @import igraph
 #' @import data.table
diff --git a/R/KWCounts.R b/R/KWCounts.R
index 89166be..d8869f0 100644
--- a/R/KWCounts.R
+++ b/R/KWCounts.R
@@ -39,6 +39,16 @@
 #' @note For large number of exceptions and/or large data.frame computation of
 #' keyword counts may take some time.
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' # Load PGR passport database
 #' GN <- GN1000
 #'
@@ -60,6 +70,12 @@
 #' bp <- barplot(table(GNKWCouts$COUNT),
 #'               xlab = "Word count", ylab = "Frequency", col = "#CD5555")
 #' text(bp, 0, table(GNKWCouts$COUNT),cex=1,pos=3)
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso \code{\link[stringi]{stri_count}}
 #' @return A data frame with the keyword counts for each record.
 #' @import data.table
diff --git a/R/KWIC.R b/R/KWIC.R
index 165bcab..8c57807 100644
--- a/R/KWIC.R
+++ b/R/KWIC.R
@@ -61,6 +61,16 @@
 #'
 #' @encoding UTF-8
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' # Load PGR passport database
 #' GN <- GN1000
 #'
@@ -88,6 +98,12 @@
 #' GN[1001,3] <- ""
 #' GNKWIC <- KWIC(GN, GNfields)
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @import data.table
 #' @importFrom stringi stri_split_fixed
 #' @export KWIC
diff --git a/R/MergeProbDup.R b/R/MergeProbDup.R
index 9e91a37..324da31 100644
--- a/R/MergeProbDup.R
+++ b/R/MergeProbDup.R
@@ -26,6 +26,16 @@
 #'   and semantic probable duplicate sets.
 #' @seealso \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{SplitProbDup}}
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #' #' # Load PGR passport database
 #' GN <- GN1000
@@ -71,6 +81,12 @@
 #' GNdupMerged <- MergeProbDup(GNdupSplit[[1]], GNdupSplit[[3]])
 #' 
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @import data.table
 #' @importFrom methods is
 #' @export
diff --git a/R/ParseProbDup.R b/R/ParseProbDup.R
index 80b7efc..bc84553 100644
--- a/R/ParseProbDup.R
+++ b/R/ParseProbDup.R
@@ -37,6 +37,16 @@
 #'   retrieved columns(fields) the prefix \code{K*} indicates the KWIC index of 
 #'   origin.
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #' 
 #' #' # Load PGR passport database
@@ -80,6 +90,12 @@
 #' GNdupParsed <- ParseProbDup(GNdup)
 #' 
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso 
 #'   \code{\link[PGRdup]{ProbDup}},
 #' @import data.table
diff --git a/R/ProbDup.R b/R/ProbDup.R
index 327584a..d00ce30 100644
--- a/R/ProbDup.R
+++ b/R/ProbDup.R
@@ -152,6 +152,16 @@
 #'   \url{https://journal.r-project.org/archive/2014/RJ-2014-011/index.html}.
 #' @encoding UTF-8
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #'
 #' # Method "a"
@@ -255,6 +265,12 @@
 #' GNdupc
 #'
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso \code{\link[PGRdup]{KWIC}}, \code{\link[PGRdup]{DoubleMetaphone}}
 #'   \code{\link[stringdist:stringdist]{stringdistmatrix}},
 #'   \code{\link[utils]{adist}}, \code{\link[PGRdup]{print.ProbDup}}
diff --git a/R/ReconstructProbDup.R b/R/ReconstructProbDup.R
index e974714..026977e 100644
--- a/R/ReconstructProbDup.R
+++ b/R/ReconstructProbDup.R
@@ -42,6 +42,16 @@
 #'   phonetic and semantic probable duplicate sets according to the instructions
 #'   specified under clerical review.
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #'
 #' # Load PGR passport database
@@ -107,6 +117,12 @@
 #' lapply(GNdup2, nrow)
 #' 
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{ReviewProbDup}}
 #' @import data.table
 #' @importFrom stringi stri_count_fixed
diff --git a/R/ReviewProbDup.R b/R/ReviewProbDup.R
index 41eaf70..f69f6b4 100644
--- a/R/ReviewProbDup.R
+++ b/R/ReviewProbDup.R
@@ -94,6 +94,16 @@
 #' @seealso \code{\link[PGRdup]{DataClean}}, \code{\link[PGRdup]{KWIC}},
 #'   \code{\link[PGRdup]{ProbDup}}
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #'
 #' # Load PGR passport database
@@ -147,6 +157,12 @@
 #' write.csv(file="Duplicate sets for review.csv", x=RevGNdup)
 #'
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @import data.table
 #' @importFrom methods is
 #' @export
diff --git a/R/SplitProbDup.R b/R/SplitProbDup.R
index 89944d9..e4a8487 100644
--- a/R/SplitProbDup.R
+++ b/R/SplitProbDup.R
@@ -28,6 +28,16 @@
 #'   accessions present in each (\code{list1} and \code{list2}).
 #' @seealso \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{MergeProbDup}}
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #' # Load PGR passport database
 #' GN <- GN1000
@@ -70,6 +80,12 @@
 #' GNdupSplit <- SplitProbDup(GNdup, splitat = c(10, 10, 10))
 #' 
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @import data.table
 #' @importFrom methods is
 #' @export
diff --git a/R/ViewProbDup.R b/R/ViewProbDup.R
index 0173ef6..df0e3cd 100644
--- a/R/ViewProbDup.R
+++ b/R/ViewProbDup.R
@@ -79,6 +79,16 @@
 #'   grouped together using \code{\link[gridExtra]{gridExtra-package}}.
 #'   
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #' 
 #' # Method "b and c"
@@ -146,7 +156,13 @@
 #'library(gridExtra)                                                    
 #'grid.arrange(GNdupcView$SummaryGrob)                          
 #' 
-#' }       
+#' }   
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#'     
 #' @seealso \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{DisProbDup}}, 
 #'   \code{\link[PGRdup]{DataClean}}, \code{\link[ggplot2]{ggplot}}, 
 #'   \code{\link[gridExtra]{gridExtra-package}}
diff --git a/R/read.genesys.R b/R/read.genesys.R
index 964e43b..a0c8e45 100644
--- a/R/read.genesys.R
+++ b/R/read.genesys.R
@@ -44,11 +44,27 @@
 #'   to console.
 #' @return A data.frame with the flat file form of the genesys data.
 #' @examples
+#' 
+#' \dontshow{
+#' threads_dt <- data.table::getDTthreads()
+#' threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+#' data.table::setDTthreads(2)
+#' 
+#' data.table::setDTthreads(2)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+#' }
+#' 
 #' \dontrun{
 #' # Import the DwC-Germplasm zip archive "genesys-accessions-filtered.zip"
 #' PGRgenesys <- read.genesys("genesys-accessions-filtered.zip",
 #'                            scrub.names.space = TRUE, readme = TRUE)
 #' }
+#' 
+#' \dontshow{
+#' data.table::setDTthreads(threads_dt)
+#' Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+#' }
+#' 
 #' @seealso \code{\link[data.table]{data.table}}
 #' 
 #' @import data.table
diff --git a/man/AddProbDup.Rd b/man/AddProbDup.Rd
index 21cf633..5cabe13 100644
--- a/man/AddProbDup.Rd
+++ b/man/AddProbDup.Rd
@@ -52,6 +52,16 @@ When any primary ID/key records in the fuzzy, phonetic or semantic
   on the database \code{db} before running this function.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 #' # Load PGR passport database
@@ -95,6 +105,12 @@ GNdup <- ProbDup(kwic1 = GNKWIC, method = "a", excep = exep, fuzzy = TRUE,
 GNwithdup <-  AddProbDup(pdup = GNdup, db = GN1000, addto = "I")                  
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{DataClean}}, \code{\link[PGRdup]{KWIC}},
diff --git a/man/DisProbDup.Rd b/man/DisProbDup.Rd
index 661a454..564e47d 100644
--- a/man/DisProbDup.Rd
+++ b/man/DisProbDup.Rd
@@ -37,6 +37,16 @@ as an additional data frame \code{DisjointDuplicates} in an object of class
 \code{ProbDup}
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 # Load PGR passport database
@@ -86,6 +96,12 @@ disGNdup2 <- DisProbDup(GNdup, combine = c("F", "P", "S"))
 lapply(disGNdup2, nrow)
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{ProbDup}}
diff --git a/man/KWCounts.Rd b/man/KWCounts.Rd
index 6de8a99..bd39595 100644
--- a/man/KWCounts.Rd
+++ b/man/KWCounts.Rd
@@ -39,6 +39,16 @@ For large number of exceptions and/or large data.frame computation of
 keyword counts may take some time.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 # Load PGR passport database
 GN <- GN1000
 
@@ -60,6 +70,12 @@ GNKWCouts <- KWCounts(GN, GNfields, exep)
 bp <- barplot(table(GNKWCouts$COUNT),
               xlab = "Word count", ylab = "Frequency", col = "#CD5555")
 text(bp, 0, table(GNKWCouts$COUNT),cex=1,pos=3)
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[stringi]{stri_count}}
diff --git a/man/KWIC.Rd b/man/KWIC.Rd
index 4333a0c..f1e3997 100644
--- a/man/KWIC.Rd
+++ b/man/KWIC.Rd
@@ -42,6 +42,16 @@ Cleaning of the data the input fields(columns) using the
 suggested before running this function.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 # Load PGR passport database
 GN <- GN1000
 
@@ -69,6 +79,12 @@ GN[1001:1005,] <- GN[1:5,]
 GN[1001,3] <- ""
 GNKWIC <- KWIC(GN, GNfields)
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \references{
 Kn\enc{ü}{ue}pffer, H. 1988. "The European Barley Database of the ECP/GR:
diff --git a/man/MergeProbDup.Rd b/man/MergeProbDup.Rd
index 1571aac..942cc84 100644
--- a/man/MergeProbDup.Rd
+++ b/man/MergeProbDup.Rd
@@ -20,6 +20,16 @@ An object of class \code{ProbDup} with the merged list of  fuzzy, phonetic
 one.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 #' # Load PGR passport database
 GN <- GN1000
@@ -65,6 +75,12 @@ GNdupSplit <- SplitProbDup(GNdup, splitat = c(10, 10, 10))
 GNdupMerged <- MergeProbDup(GNdupSplit[[1]], GNdupSplit[[3]])
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{SplitProbDup}}
diff --git a/man/ParseProbDup.Rd b/man/ParseProbDup.Rd
index bfb3ccf..a52369b 100644
--- a/man/ParseProbDup.Rd
+++ b/man/ParseProbDup.Rd
@@ -31,6 +31,16 @@ A data frame of the long/narrow form of the probable duplicate sets
 \code{ParseProbDup} converts an object of class \code{ProbDup} to a data frame for export.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 #' # Load PGR passport database
@@ -74,6 +84,12 @@ GNdup <- ProbDup(kwic1 = GNKWIC, method = "a", excep = exep, fuzzy = TRUE,
 GNdupParsed <- ParseProbDup(GNdup)
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{ProbDup}},
diff --git a/man/ProbDup.Rd b/man/ProbDup.Rd
index 802f6e9..acfa8f8 100644
--- a/man/ProbDup.Rd
+++ b/man/ProbDup.Rd
@@ -191,6 +191,16 @@ As the number of keywords in the KWIC indexes increases, the memory
   function, which is made use of here for string matching.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 # Method "a"
@@ -294,6 +304,12 @@ GNdupc <- ProbDup(kwic1 = GN1KWIC, kwic2 = GN2KWIC, method = "c",
 GNdupc
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \references{
 van der Loo, M. P. J. 2014. "The Stringdist Package for
diff --git a/man/ReconstructProbDup.Rd b/man/ReconstructProbDup.Rd
index 640130a..c9d0441 100644
--- a/man/ReconstructProbDup.Rd
+++ b/man/ReconstructProbDup.Rd
@@ -35,6 +35,16 @@ identical integers in the column \code{SPLIT} other than the default \code{0}
 are reassembled into a new set.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 # Load PGR passport database
@@ -100,6 +110,12 @@ lapply(disGNdup, nrow)
 lapply(GNdup2, nrow)
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{ReviewProbDup}}
diff --git a/man/ReviewProbDup.Rd b/man/ReviewProbDup.Rd
index 8455f1d..6e068a1 100644
--- a/man/ReviewProbDup.Rd
+++ b/man/ReviewProbDup.Rd
@@ -101,6 +101,16 @@ When any primary ID/key records in the fuzzy, phonetic or semantic
   which may be safely ignored.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 # Load PGR passport database
@@ -154,6 +164,12 @@ RevGNdup <- edit(RevGNdup)
 write.csv(file="Duplicate sets for review.csv", x=RevGNdup)
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{DataClean}}, \code{\link[PGRdup]{KWIC}},
diff --git a/man/SplitProbDup.Rd b/man/SplitProbDup.Rd
index 168f065..096177b 100644
--- a/man/SplitProbDup.Rd
+++ b/man/SplitProbDup.Rd
@@ -22,6 +22,16 @@ A list with the the divided objects of class \code{ProbDup}
 basis of set counts.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 # Load PGR passport database
 GN <- GN1000
@@ -64,6 +74,12 @@ GNdup <- ProbDup(kwic1 = GNKWIC, method = "a", excep = exep, fuzzy = TRUE,
 GNdupSplit <- SplitProbDup(GNdup, splitat = c(10, 10, 10))
 
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{MergeProbDup}}
diff --git a/man/ViewProbDup.Rd b/man/ViewProbDup.Rd
index 133e293..4a16bd3 100644
--- a/man/ViewProbDup.Rd
+++ b/man/ViewProbDup.Rd
@@ -90,6 +90,16 @@ When any primary ID/key records in the fuzzy, phonetic or semantic
   grouped together using \code{\link[gridExtra]{gridExtra-package}}.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 
 # Method "b and c"
@@ -157,7 +167,13 @@ GNdupcView <- ViewProbDup(GNdupc, GN1, GN2, "SourceCountry", "SourceCountry",
 library(gridExtra)                                                    
 grid.arrange(GNdupcView$SummaryGrob)                          
 
-}       
+}   
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+    
 }
 \seealso{
 \code{\link[PGRdup]{ProbDup}}, \code{\link[PGRdup]{DisProbDup}}, 
diff --git a/man/read.genesys.Rd b/man/read.genesys.Rd
index e5759bf..d4438bf 100644
--- a/man/read.genesys.Rd
+++ b/man/read.genesys.Rd
@@ -41,11 +41,27 @@ The argument \code{readme} can be used to print the readme file in the
 archive to console, if required.
 }
 \examples{
+
+\dontshow{
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+data.table::setDTthreads(2)
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+}
+
 \dontrun{
 # Import the DwC-Germplasm zip archive "genesys-accessions-filtered.zip"
 PGRgenesys <- read.genesys("genesys-accessions-filtered.zip",
                            scrub.names.space = TRUE, readme = TRUE)
 }
+
+\dontshow{
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+}
+
 }
 \seealso{
 \code{\link[data.table]{data.table}}
diff --git a/src/PGRdup.so b/src/PGRdup.so
index 57eaa09..98f516e 100644
Binary files a/src/PGRdup.so and b/src/PGRdup.so differ
diff --git a/vignettes/Introduction.Rmd b/vignettes/Introduction.Rmd
index 9960580..b223d0c 100644
--- a/vignettes/Introduction.Rmd
+++ b/vignettes/Introduction.Rmd
@@ -49,6 +49,15 @@ out_type <- ifelse(identical (out_type, vector(mode = "logical", length = 0)),
                    "latex", out_type)
 ```
 
+```{r, echo=FALSE}
+# Restrict threads for avoid elapsed threshold error in CRAN check
+threads_dt <- data.table::getDTthreads()
+threads_OMP <- Sys.getenv("OMP_THREAD_LIMIT")
+
+data.table::setDTthreads(2)
+Sys.setenv(`OMP_THREAD_LIMIT` = 2)
+```
+
 ```{r, results='asis', echo=FALSE}
 switch(out_type,
     html = {cat("<p>1. ICAR-National Bureau of Plant Genetic Resources, New Delhi, India.</p>
@@ -1283,3 +1292,9 @@ sessionInfo()
 ```
 
 ## References
+
+```{r, echo=FALSE}
+data.table::setDTthreads(threads_dt)
+Sys.setenv(`OMP_THREAD_LIMIT` = threads_OMP)
+```
+
diff --git a/vignettes/Introduction.pdf b/vignettes/Introduction.pdf
index 4933c45..2d7a714 100644
Binary files a/vignettes/Introduction.pdf and b/vignettes/Introduction.pdf differ