IntelliJ IDEA 13 CE consuming lots of CPU

I'm posting this comment by K P as an answer, because K P does not have enough reputation.

It just needed some more memory to prevent repeated garbage collection. I found the file idea.vmoptions [aka idea64.exe.vmoptions] and increased the memory for InteiiJ to run (Xms = 512m and Xmx = 2048). The CPU usage has come down to 0.2 - 10% when nothing is being done on it.

Go to your home folder, then navigate to .IntelliJIdea13\config\options

Edit the file project.default.xml by changing the VM_PARAMETERS Xmx and Xms as follows:

<option name="VM_PARAMETERS" value="-Xmx2048m -Xms512m -XX:MaxPermSize=250m -ea" />

It decreased the CPU usage to 50%.

Try clean up cache and restart. In Intellij 14 go to menu File -> Invalidate Caches / Restart...

As other said,increasing memory heap of IDEA is work, my IDEA version is 2016.3.4, following is setting way

1. Do one of the following:
   • Use the main menu command Help | Edit Custom VM Options to create a copy of the idea.vmoptions file in the user home. Refer to Edit Custom VM Options for details.
   • Copy the existing file from the IntelliJ IDEA installation folder somewhere and save the path to this location in the environment variable IDEA_VM_OPTIONS.
   • Copy the existing file /bin/idea.exe.vmoptions or /bin/idea64.exe.vmoptions from the IntelliJ IDEA installation folder into the location under your user home.