https://www.reddit.com/r/Jetbrains/comments/1mbbkao/boosting_intellij_performance_my_final_setup/

-Xss1m
-Xmx4G
-XX:SoftRefLRUPolicyMSPerMB=7
-XX:+UseG1GC
-XX:MaxGCPauseMillis=100
-XX:G1HeapRegionSize=16m
-XX:NewRatio=2
-XX:InitiatingHeapOccupancyPercent=66
-Dide.no.platform.update=true

Quick notes on the logic

• Xss1m: Reduces memory used per thread.
  • Default is 2m, which is fine for Java, but I'm working with Angular + LSP + ESLint + Prettier, so lots of threads = more memory pressure.
• XX:+UseG1GC: Forces G1GC. This is usually the default, but better to be explicit.
• XX:MaxGCPauseMillis=100:
  • Default is 200.
  • Tells G1GC to aim for <100ms pause times. Doesn’t guarantee it, but helps reduce UI stutters during GC.
• XX:G1HeapRegionSize=16m:
  • Larger regions mean fewer to manage so, less GC overhead.
  • Max is 32m, but I had better results with 16m.
• Xmx4G: Total heap size (about 1/4 — 1/3 of your total RAM)
• XX:SoftRefLRUPolicyMSPerMB=7:
  • Collects soft refs after ~30 seconds.
  • Xmx=4G: 30s / 4G → ~7
  • Keeps memory usage under control when the IDE is idle
• XX:NewRatio=2:
  • New gen = 1/(N+1) = 1/3 of heap
  • Old gen = N/(N+1) = 2/3 of heap
  • This ratio works well for large and medium projects
• XX:InitiatingHeapOccupancyPercent=66:
  • Triggers GC when heap is about 66% full (so when old gen is full)
  • Aligned with the NewRatio=2 setting
  • If you use NewRatio=1, set this to 50 instead
• Dide.no.platform.update=true:
  • Only set this if you're using JetBrains Toolbox
  • Prevents IntelliJ from trying to self-update (Toolbox handles it).