High CPU usage


Hello I just got a fresh installation of Clion, and basically I cannot use because right from the beginning it's using a lot of system resources, even though it should not be doing anything significant. I am running macOS Mojave on 2015 MBP 16gb RAM


I get the same issue, cpu usage on quad core i7 2018 macbook pro  goes up to 500% and stays there for a long time. This happens failly regularly. The solution is to quit intellij, restart it, and generally the problem goes.

It is more likely to happen shortly after starting intellij, but also happens randomly when intellij has been idle for some time. The first warning sign is the laptops fans start up, sounding like a helicopter landing. When this happens, I go to activity monitor, and it is either skype, onedrive or intellij which has gone into overdrive for no obvious reason.  

Sometimes, if I dont mind the noise, I let it run, and after a minute or so, the CPU drops again. no idea what its doing.  Scanning your whole HD?  SETI?



I had similar problem after upgrading to IntelliJ IDEA 19.2. I attached to it with VisualVM and after some profiling it turned out that was caused by a third-party plugin. (Attlasian's bitbucket linkify or something like that in my case).

I'm writing this in hope that it might be helpful for somebody else too.


This happens on startup and every time I input new code. It is really bugging me because the fan is getting really loud. 


Could you please try disabling `C/C++ | Data flow analysis`, `C/C++ | Unused code` and `General | Simlifiable statement` inspections on the `Preferences | Editor | Inspections` tab? Does that help?


I have the same issue after updating to 19.2 running on Windows 10.





Same issue with 2019.2 on Mac.. Unable to use the mac bcoz IntelliJ utilization of CPU is > 350%


I have her the same issue on my MacBook Pro 2018 i7 with 16 GB Ram (2019.2). This happend on every startup and CPU is > 500% for a few minutes. Fan is very loud and the Mac gets very hot.



It may occur because of the lower heap size that is assigned to memory. 

Try increasing the heap size.

How to increase heap size: https://www.jetbrains.com/help/idea/increasing-memory-heap.html


I have similar problems with Goland running on ubuntu 18.04 with i7 and 16GB or RAM. I've allocated 4GB for the JVM but the cpu usage still goes up tp 500-600% CPU every time the code change and the code analysis kicked in.


Unfortunately it doesn't help.


Please enable memory indicator (`Preferences | Appearance & Behavior | Appearance | Show memory indicator`) and keep an eye on it for some time (the indicator will appear in the bottom right corner of the CLion window). If it is close to the limit at the time when you are experiencing the problems, then try increasing the Xmx JVM option according to this guide. Sometimes CPU usage may decrease if you provide CLion with enough heap memory. 

We are working hard on CLion performance improvements and are planning that CLion 2019.1 will contain some important fixes. Please accept our sincere apologies for the inconvenience.


Did you check with top/htop how many processes clion spawns ? In my case I see up to 10-12 java processes each consuming CPU and a couple of GB or RAM. It so bad that whole workstation (Xeon + 68 GB RAM) becomes unresponsive. 

I switched to Visual Studio Code that consumes almost nothing and I am checking Clion every update is made. But truly speaking I don't think they will fix it. 


I'm experiencing the same problem... Too bad... I've just bought it ^^

I confirm Visual Studio Code has not this kind of problem, but it has so many others that I'd like to stick to CLion...

But if it's unusable, I won't have a choice :'(

In the mean time, I've disactivated every C/C++ inspections, and it seems to be way better...

But the simple syntax coloration when opening a new file makes my PC work so hard that I can cook an egg on it.

[Edit] I'm working in a VM, that doesn't help.


I experience the same problems as other people commented.
When Idea is Initially opened the CPU is at 100% (i7-8650U, Windows 10) long after index is done.
Even a slightest change in code or in the ide, trigger another cpu bottleneck

Bellow is the excerpt of Activity monitor, when cpu is at 100% :

%CPU Subsystem

13.2 <Process total CPU usage>
6.3 <JIT compiler>
3.9 <infrastructure: BaseDataReader: output stream of fsnotifier64.exe>
1.5 <unidentified: UI thread>
0.7 editor.textarea (in com.intellij.openapi)
0.7 ide (in com.intellij)
0.7 <unidentified: Periodic tasks thread>


Another activity :

%CPU Subsystem

1.2 <JIT compiler>
0.7 <Process total CPU usage>


Hi, I experience this several times a day, sometimes not at all, sometimes like two times per hour. IDEA eats all my CPU (400%+), computer is unusable during that time. I tried to make a screenshot but it's not possible - the screenshot is done several seconds AFTER the peak when the load starts to be OK again.
Right now while I'm writing this: I woke up my PC after night, didn't touch IDEA yet (have two projects/windows loaded from yesterday, Scala and Rust) and it makes huge CPU load every few minutes (!), like 3 times during writing this (including worthless effort to make the screenshot).
During the load, IDEA is 7-8x in the 10 most CPU consuming processes (the others are usually browser or some Electron-based shit)
PLEASE help.
Ubuntu 19.04, i7 7820HQ, 32 GB RAM. IDEA has 3G heap size.


I doubt that they will solve performance issues. I have been using Clion for a couple of years and it sucks with large projects the same way it was a couple of versions ago.  If they want to publish reliable performance numbers they shall take a fixed revision of some open source projects (linux kernel + a few others) and constantly publish time and CPU usage of indexing using the same hardware.

I opened a ticket for 5k lines of code that are killing 128 GB workstation and there is no reaction.



>I opened a ticket for 5k lines of code that are killing 128 GB workstation and there is no reaction.

@Michal, is it a YouTrack issue? Could you please share the link?


For everyone:

There is no "general cause" for all performance problem. In order to understand what problem you're facing in particular we need some diagnostic information. Please send automatically generated thread dumps if you have them in the logs folder (Help | Show Log in …) to clion-support at jetbrains.com or, if there are no dumps, please capture a CPU snapshot and send it to us.


Michal, thanks for sharing the link. The problem you've faced is indeed serious and, unfortunately, it's not easy to fix it. Right now we are working on the related issue - https://youtrack.jetbrains.com/issue/CPP-12362. The fix might help in your case too. Please follow CPP-12362 to get updates.


Having same problem. IntelliJ uses 800% CPU and heats up my mac so much. I use 2020.3.4 Ultimate Edition. I have to periodically shutdown Intellij and restart after some time. It is very annoying. Gets worse if i open more than one project.


It sound like after reading all of these comments that it is just the IDE indexing.  This will happen at first launch (for each project as well).  Be sure to run only one instance as well (not several projects at once).  I experience 500% + CPU usage as well.  But it is only for indexing.  Indexing can also happen after you add a new package (for example some node package).  The question is after it is done indexing, and you will know based on the bar at the bottom of PHP Storm; is the CPU usage still high?  Because mine is hovering around 5 to 10%.

Note the initial left hand side while it was booting up and indexing the files.

Hypothesis:  You have a lot of code in your project.  You may want to do an ignore on some directories which I am not 100% sure how to do in PHPS.


Same problem for me and I'm running a M1 with 64GB of ram.  I'm literally not able to type more than a few keys without the IDE freezing up.


I gave up tracing/tweaking CLion. I switched to Visual Studio Code configured with external clangd. Fast, snappy, no freezing.


Hello! Sorry for the inconvenience. Do you experience this on startup? Does the value decrease over time?


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