Performance tuning parameters for IntelliJ IDEA. Add these params in idea64.exe.vmoptions or idea.exe.vmoptions file in IntelliJ IDEA. If you are using JDK 8.x, please knock off PermSize and MaxPermSize parameters from the tuning configuration.

IntelliJ_IDEA__Perf_Tuning.txt

-server
-Xms2048m
-Xmx2048m
-XX:NewSize=512m
-XX:MaxNewSize=512m
-XX:PermSize=512m
-XX:MaxPermSize=512m
-XX:+UseParNewGC
-XX:ParallelGCThreads=4
-XX:MaxTenuringThreshold=1
-XX:SurvivorRatio=8
-XX:+UseCodeCacheFlushing
-XX:+UseConcMarkSweepGC
-XX:+AggressiveOpts
-XX:+CMSClassUnloadingEnabled
-XX:+CMSIncrementalMode
-XX:+CMSIncrementalPacing
-XX:+CMSParallelRemarkEnabled
-XX:CMSInitiatingOccupancyFraction=65
-XX:+CMSScavengeBeforeRemark
-XX:+UseCMSInitiatingOccupancyOnly
-XX:ReservedCodeCacheSize=64m
-XX:-TraceClassUnloading
-ea
-Dsun.io.useCanonCaches=false

Intellij 2017.3 will moan about the code cache size, it should be around:
-XX:ReservedCodeCacheSize=256m

or remove the setting altogether.

-XX:ReservedCodeCacheSize=64m threw a warning on MacOS HighSierra. Considering increasing to 240m or more.

Pay attention, alot of those options are deprecated and will lead in not starting the application.

Unix Debian with Phpstorm from snap

I had to do this:

Remove

-XX:+UseParNewGC
-XX:PermSize=512m
-XX:MaxPermSize=512m
-XX:+UseConcMarkSweepGC
-XX:+AggressiveOpts
-XX:+CMSIncrementalMode
-XX:+CMSIncrementalPacing
 
Replace
-XX:-TraceClassUnloading -Xlog:class+unload=off

This is my current file for PHPStorm:
~/.PhpStorm2019.2/config/phpstorm64.vmoptions

-server
-Xms1g
-Xmx4g
-XX:NewSize=512m
-XX:MaxNewSize=1g
-XX:ParallelGCThreads=4
-XX:MaxTenuringThreshold=1
-XX:SurvivorRatio=8
-XX:+UseCodeCacheFlushing
-XX:+CMSClassUnloadingEnabled
-XX:+CMSParallelRemarkEnabled
-XX:CMSInitiatingOccupancyFraction=65
-XX:+CMSScavengeBeforeRemark
-XX:+UseCMSInitiatingOccupancyOnly
-XX:ReservedCodeCacheSize=256m
-Xlog:class+unload=off
-ea
-Dsun.io.useCanonCaches=false

thanks reloxx13
it works on Pycharm 2019.2.1 windows

Thanks Dude ✌️

reloxx's config is good. also add editor.zero.latency.typing=true in idea.properties (Help > Edit Custom Properties).

Thanks reloxx13

This is my current file for PHPStorm (PhpStorm2019.1) (Windows):

-server
-Xss256k
-Xms1536m
-Xmx1536m
-Xmn512m

-XX:MetaspaceSize=350m
-XX:MaxMetaspaceSize=350m
-XX:SurvivorRatio=8
-XX:CMSFullGCsBeforeCompaction=0
-XX:ReservedCodeCacheSize=240m
-XX:MaxNewSize=1000m
-XX:NewSize=512m
-XX:ParallelGCThreads=4
-XX:MaxTenuringThreshold=1
-XX:CMSInitiatingOccupancyFraction=65

-XX:+CMSScavengeBeforeRemark
-XX:+CMSPermGenSweepingEnabled
-XX:+UseCMSInitiatingOccupancyOnly
-XX:+UseCMSCompactAtFullCollection
-XX:+HeapDumpOnOutOfMemoryError
-XX:+UseCodeCacheFlushing
-XX:-TraceClassUnloading
-XX:+CMSClassUnloadingEnabled
-XX:+CMSParallelRemarkEnabled

-ea
-Dsun.io.useCanonCaches=false

All settings here are still using CMS GC. Anyone trying G1GC options instead?

-server
-XX:MetaspaceSize=128M
-XX:MaxMetaspaceSize=512M
-XX:+AlwaysPreTouch
-Xms128m
-Xmx512M
-XX:ReservedCodeCacheSize=512m
-XX:+UseG1GC
-XX:+UseStringDeduplication
-XX:AutoBoxCacheMax=20000
-ea
-Dsun.io.useCanonCaches=false
-Dsun.awt.keepWorkingSetOnMinimize=true
-Djava.net.preferIPv4Stack=true
-Djdk.http.auth.tunneling.disabledSchemes=""
-Djsse.enablesSNIExtension=false
-XX:+HeapDumpOnOutOfMemoryError
-XX:-OmitStackTraceInFastThrow
-Dfile.encoding=UTF-8
-Duser.name=tshit11

-server
-XX:MetaspaceSize=128M
-XX:MaxMetaspaceSize=512M
-XX:+AlwaysPreTouch
-Xms128m
-Xmx512M
-XX:ReservedCodeCacheSize=512m
-XX:+UseG1GC
-XX:+UseStringDeduplication
-XX:AutoBoxCacheMax=20000
-ea
-Dsun.io.useCanonCaches=false
-Dsun.awt.keepWorkingSetOnMinimize=true
-Djava.net.preferIPv4Stack=true
-Djdk.http.auth.tunneling.disabledSchemes=""
-Djsse.enablesSNIExtension=false
-XX:+HeapDumpOnOutOfMemoryError
-XX:-OmitStackTraceInFastThrow
-Dfile.encoding=UTF-8
-Duser.name=tshit11

Thanks for share! Recommend adding for solve UI issues

-Dhidpi=true
-Dsun.java2d.uiScale.enabled=false
-Dide.ui.scale=1.0

@indiff there's a username in those options

A merged from @indiff, @iuriimattos and with JetBrains PhpStorm 2023.2.1RC from a fresh win11 installation default options and some old stuff, I use it in host and client (wsl2) vmoptions.

-Dawt.java2d.opengl=true
-Dawt.lock.fair=true
-Dawt.useSystemAAFontSettings=lcd
-Dfile.encoding=UTF-8
-Dhidpi=true
-Dide.ui.scale=1.0
-Djava.net.preferIPv4Stack=true
-Djbr.catch.SIGABRT=true
-Djdk.attach.allowAttachSelf=true
-Djdk.http.auth.tunneling.disabledSchemes=""
-Djdk.module.illegalAccess.silent=true
-Djsse.enablesSNIExtension=false
-Dkotlinx.coroutines.debug=off
-Dsun.awt.keepWorkingSetOnMinimize=true
-Dsun.io.useCanonCaches=false
-Dsun.java2d.metal=true
-Dsun.java2d.uiScale.enabled=false
-Dsun.tools.attach.tmp.only=true

-XX:+AlwaysPreTouch
-XX:+CMSClassUnloadingEnabled
-XX:+CMSParallelRemarkEnabled
-XX:+CMSPermGenSweepingEnabled
-XX:+CMSScavengeBeforeRemark
-XX:+HeapDumpOnOutOfMemoryError
-XX:+HeapDumpOnOutOfMemoryError
-XX:+HeapDumpOnOutOfMemoryError
-XX:+IgnoreUnrecognizedVMOptions
-XX:+TieredCompilation
-XX:+UseCMSCompactAtFullCollection
-XX:+UseCMSInitiatingOccupancyOnly
-XX:+UseCodeCacheFlushing
-XX:+UseConcMarkSweepGC
-XX:+UseG1GC
-XX:+UseStringDeduplication
-XX:-OmitStackTraceInFastThrow
-XX:-TraceClassUnloading
-XX:AutoBoxCacheMax=20000
-XX:CICompilerCount=2
-XX:CMSFullGCsBeforeCompaction=0
-XX:CMSInitiatingOccupancyFraction=65
-XX:CompileCommand=exclude,com/intellij/openapi/vfs/impl/FilePartNodeRoot,trieDescend
-XX:ConcGCThreads=4
-XX:MaxMetaspaceSize=512m
-XX:MaxNewSize=1g
-XX:MaxTenuringThreshold=1
-XX:MetaspaceSize=512m
-XX:NewRatio=1
-XX:NewSize=512m
-XX:ParallelGCThreads=4
-XX:ReservedCodeCacheSize=512m
-XX:SoftRefLRUPolicyMSPerMB=50
-XX:SurvivorRatio=8

-Xms1g
-Xmx4g

-ea