Added debouncing update

src/extension.ts

@@ -1,14 +1,14 @@
 import * as vscode from 'vscode'
 import { getDecorations } from './decoration'
+import { debounce } from './utils'
 
 export function activate(context: vscode.ExtensionContext) {
     let tokenSource: vscode.CancellationTokenSource
 
     let currentDecorations: Awaited<ReturnType<typeof getDecorations>> = []
 
-    context.subscriptions.push(
-        vscode.window.onDidChangeTextEditorSelection(async (event) => {
-            tokenSource?.cancel()
+    const updateDecorations = debounce(
+        async (event: vscode.TextEditorSelectionChangeEvent) => {
             tokenSource = new vscode.CancellationTokenSource()
 
             const token = tokenSource.token
@@ -28,6 +28,14 @@ export function activate(context: vscode.ExtensionContext) {
                     new vscode.Selection(line, 0, line, 0),
                 ])
             )
+        },
+        () => 50
+    )
+
+    context.subscriptions.push(
+        vscode.window.onDidChangeTextEditorSelection((event) => {
+            tokenSource?.cancel()
+            updateDecorations(event)
         })
     )
 }

src/utils.ts

@@ -0,0 +1,16 @@
+export function debounce<T extends (...args: never[]) => unknown>(
+    fn: T,
+    getMs: () => number
+) {
+    let timer: NodeJS.Timeout
+    return (...args: Parameters<T>) => {
+        clearTimeout(timer)
+
+        const ms = getMs()
+        if (ms > 0) {
+            timer = setTimeout(() => fn(...args), getMs())
+        } else {
+            fn(...args)
+        }
+    }
+}