Why is IntelliJ 13 IDEA so slow after upgrading from version 12?

I had the same problem with slowness in IntelliJ 13 after upgrading from 12. What worked for me was editing the idea64.vmoptions in the bin folder and setting the max heap to 8 GB (was 512 MB) and the Max PermGen to at least 1GB (was 300MB).Example below:

-Xms128m
-Xmx8192m
-XX:MaxPermSize=1024m

Upon restart it was much faster.

For IntelliJ 2020 going back to 2017 on Mac /Applications/IntelliJ IDEA.app/Contents/bin/idea.vmoptions

On a Mac, this file is located in this path:

For IntelliJ 14 or 15 on Mac /Applications/IntelliJ IDEA 14.app/Contents/bin/idea.vmoptions

For IntelliJ 13 on Mac /Users/yourusername/Library/Preferences/IntelliJIdea13/idea.vmoptions

IntelliJ's updater (since 2017) seems to roll this change back, so you may need to re-apply it after updating.

On Ubuntu Linux, this file is located in this path relative to the install directory:

idea-IU-135.475/bin/idea64.vmoptions

and for 2016.2:

 ~/.IdeaIC2016.2/idea64.vmoptions

On Windows 10 (Community edition shown here) these files are located in:

C:\Program Files (x86)\JetBrains\IntelliJ IDEA Community Edition 2016.1.3\bin\idea64.exe.vmoptions

In my case, GIT integration appears to be causing the editor to be frustratingly slow with 13.

While typing, even comments, with GIT integration turned on, after about 30 characters, the UI freezes for a second or so. Its usually not long, but very annoying.

I am using GIT 1.7.8.0. Running on Windows 7 64 with a solid state drive and 12 gigs of ram and an intel I7 with 8 CPUs. I tried various things, like updating the idea64.exe.vmoptions to use more memory, like -Xmx2400m and -XX:MaxPermSize=2400m, -XX:ParallelGCThreads=6, but it didn't fix the problem.

The git repository is 1.3 gigs with 65,000 files.

I created a new "grails" project in a new git repository, and there is no issue. I created a new grails project in the existing large git repository, and intellij is slow. I turned off git integration by opening the project settings dialog and deleting the git root, and the problem goes away.

I tried disabling all of the GIT background operations through the 13 UI, but it didn't make a difference. I also tried both GIT built-in and native modes, and it made no difference.

In my case the workaround seems to be to disable GIT integration until I need it, and to then just re-add the git root. If anyone else can verify the same problem, then we might report it as an issue.

I noticed that disabling many of the plug ins really helps speed up IntelliJ. For example, I am not developing Android Applications. Turning the plugins related to Android development off speed up load time and makes the program run much smoother on my machine.