pycharm running way slow

1. Change the inspection level

Current PyCharm versions allows you to change the type of static code analysis it performs, and also features a Power/CPU Saving feature (Click on the icon at the bottom right, next to the lock):

2. Change indexed directories
Exclude directories from being indexed which are set in the project paths but not actually required to be searched and indexed. Press ALT+CTRL+S and search for project.

3. Do memory sweeps
There is another interesting feature:

Go into the settings (File/Settings) and search for memory. In IDE Settings>Appearance -> tick Show memory indicator. A memory bar will be shown at the bottom right corner (see the picture below). Click this bar to run a garbage collection / memory sweep.

Every performance problem with PyCharm is unique, a solution that helps to one person will not work for another. The only proper way to fix your specific performance problem is by capturing the CPU profiler snapshot as described in this document and sending it to PyCharm support team, either by submitting a ticket or directly into the issue tracker.

After the CPU snapshot is analyzed, PyCharm team will work on a fix and release a new version which will (hopefully) not be affected by this specific performance problem. The team may also suggest you some configuration change or workaround to remedy the problem based on the analysis of the provided data.

All the other "solutions" (like enabling Power Save mode and changing the highlighting level) will just hide the real problems that should be fixed.