How to Manually Adjust IntelliJ IDEA VM Options for Better Performance

1. Introduction

IntelliJ IDEA ships with low‑memory defaults (minimum 128 MB, maximum 512 MB) to accommodate low‑spec machines, which can cause slow startup and sluggish operation. Most development workstations have 8 GB or 16 GB of RAM, so adjusting the VM options manually yields a smoother experience.

2. Manually Modify IDEA Settings

Check IDEA Memory Usage

Open Settings → Appearance & Behavior and enable Show memory indicator . The bottom‑right corner of the main window will then display the current heap size and usage, allowing you to verify that your changes take effect.

Edit IDEA VM Options

Open the idea64.exe.vmoptions file via Help → Edit Custom VM Options… . The default file shows the current parameters.

Typical default values are displayed below:

The three key parameters are:

1. -Xms – initial (minimum) heap size.

2. -Xmx – maximum heap size.

3. -XX:ReservedCodeCacheSize – size of the code cache.

Recommended Settings for 8 GB RAM

-server
-Xms512m
-Xmx1024m
-XX:ReservedCodeCacheSize=300m
-XX:+UseConcMarkSweepGC
-XX:SoftRefLRUPolicyMSPerMB=50
-ea
-Dsun.io.useCanonCaches=false
-Djava.net.preferIPv4Stack=true
-Djdk.http.auth.tunneling.disabledSchemes=""
-XX:+HeapDumpOnOutOfMemoryError
-XX:-OmitStackTraceInFastThrow

Recommended Settings for 16 GB RAM

server
-Xms1024m
-Xmx2048m
-XX:ReservedCodeCacheSize=500m
-XX:+UseConcMarkSweepGC
-XX:SoftRefLRUPolicyMSPerMB=50
-ea
-Dsun.io.useCanonCaches=false
-Djava.net.preferIPv4Stack=true
-Djdk.http.auth.tunneling.disabledSchemes=""
-XX:+HeapDumpOnOutOfMemoryError
-XX:-OmitStackTraceInFastThrow

Why set the initial heap size as large as 512 MB or 1024 MB? A larger -Xms equal to -Xmx prevents the JVM from repeatedly reallocating memory after each garbage‑collection cycle, improving performance.

3. Conclusion

Adjust the VM options according to your machine’s RAM and personal needs; there is no one‑size‑fits‑all configuration.

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