Seeking Advice on Optimizing PyCharm Performance for Large Projects

Hello everyone,

I'm currently working on a fairly large-scale Python project using JetBrains' PyCharm as my primary IDE. While I appreciate the wide array of features and the seamless integration with various Python tools that PyCharm offers, I've been facing some performance issues, especially as my project grows in size and complexity.

I am experiencing noticeable lag during code editing, and the IDE takes a significant amount of time to index files, which hampers my productivity. I understand that such issues can be common in large projects, but I am looking for ways to optimize PyCharm's performance to handle this better.

Does anyone have tips or best practices for optimizing PyCharm for large-scale Python projects? Specifically, I'm interested in:

  • Adjusting settings or configurations to reduce lag and improve responsiveness.
  • Efficient project structure or practices within PyCharm to enhance performance.
  • Any plugins or external tools that integrate well with PyCharm to aid in handling larger projects.

Any advice or shared experiences with managing large projects in PyCharm would be greatly appreciated!

Thank you in advance!




Hi, in general (and this is applicable to all IDEs), I would suggest avoiding very large source files, e.g. several megabytes and/or 20k+ lines of code is probably too much for a single Python file, but I've seen such projects and they caused performance issues.

PyCharm has a limit on the maximum file size it will provide intellisense for (2.5 MB if I'm not mistaken), but that can be overridden in the settings and may be the cause of performance issues as well. 

Also, if the performance issue is due to high CPU usage, it's probably a hardware limitation. If PyCharm freezes/lags but that doesn't correlate with high CPU usage, this may be an issue we should investigate. In this case, I'd appreciate a performance problem report to with data collected according to

PyCharm should index the project once when you open it first time, and then do a quick refresh when the project is reopened (though I say quick, for large projects it can still take up to a minute). If you see that the IDE completely reindexes the whole project each time, that's also an issue we should investigate.



Thank you for your detailed response. Your advice on managing large source files in IDEs, particularly regarding the limitations and settings in PyCharm, is very insightful. I wasn't aware of the 2.5 MB limit for intellisense, and your suggestion to avoid very large files makes a lot of sense to prevent performance issues.

I will check the file sizes in my project and consider splitting larger files into smaller, more manageable ones. I'll also look into the intellisense settings in PyCharm to see if adjusting them helps with the performance.

Regarding the performance issues I'm experiencing, I will monitor the CPU usage more closely to determine if it's a hardware limitation or a software issue. If I find that PyCharm is lagging without high CPU usage, I will follow your advice and submit a performance problem report to JetBrains with the necessary data.

I also noticed the reindexing behavior you mentioned. If it continues to reindex the project completely every time I open it, I will certainly consider this worth investigating further.



Regarding the settings, please check the following platform properties (

# Maximum file size (kilobytes) IDE should provide code assistance for. 
# The larger file is the slower its editor works and higher overall system memory requirements are 
# if code assistance is enabled. Remove this property or set to very large number if you need 
# code assistance for any files available regardless their size. 

# Maximum file size (kilobytes) IDE is able to open. 

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