[p5.js 2.0+ Bug Report]: Large slowdown in p5.Graphics.set() compared to v1.11.x #9000

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• WebGPU
• p5.strands
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

p5.js version

2.3.0

Web browser and version

• Chrome Version 151.0.7922.34 (Official Build) (arm64)
• Safari Version 26.5.2 (21624.2.5.11.8)
• Firefox 152.0.4 (aarch64)

Operating system

macOS 26.5.2 (25F84) Tahoe

Steps to reproduce this

Description

Calling set() on a p5.Graphics buffer is considerably slower in p5.js 2.3.0 than in 1.11.12. Note: directly modifying pixels[] performs about the same in both versions.

I first noticed the issue when trying to run the following sketch in p5.js 2.3.0: https://openprocessing.org/@megamitts/2979162

Benchmark

I made a quickly vibe coded benchmark sketch to systematically test the issue. It updates a 100 × 100 p5.Graphics buffer over multiple frames and prints the averaged results to the console.

In this test in Chrome, set() was about 6.9 times slower in 2.3.0 than in 1.11.12.

I got comparable results, with slowdowns between ~9× and ~17×, in Safari and Firefox.

Reproduction

Run the benchmark sketch in p5.js 1.11.x, then in 2.x