[2021] 3.0.3 stuttering

If you revert to an earlier patch that used to work okay, does it get better again or is still a problem?  

If versions that used to work fine are now slow, fairly clearly there is some local problem here.

In your reinstall, did you make sure there are no files or folders left under either the Steam Stellaris or Documents Stellaris locations, before installing again?

DXDIAG is a program you run from the Windows search box on the task bar. After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.

Please attach here your Documents/Paradox Interactive/Stellaris/settings.txt and pdx_settings.txt .
From your Documents/Paradox Interactive/Stellaris/logs/ folder, attach here system.log , error.log .

Please report the temperatures of your CPU and video (GPU)
1/ before starting the game up and
2/ after say 10 minutes' play.
If your PC's vendor has given you no way of reading temperatures, install
SPEEDFAN http://www.almico.com/sfdownload.php  

Eemil said: do i have to run stellaris while running dgdiag?

No.

You have a bunch of mod errors in that log, so do all testing for this issue with NO mods at all enabled please.  

That is why you get those mod errors in the log, yes. Whether that has anything to do with your game speed I don't know.

You may as well update that nVidia driver to June 2021:
Download Drivers | NVIDIA
And there are Windows update errors at the end of that dxdiag, I have seen those cause issues to our games. Run the Update app, does it start okay? If it finds anythign to apply do that and reboot. Does that help the problem at all?  

Still getting all those errors I see. Please do a full **clean** re-install:

- move any valued save games elsewhere, and user_empire_designs.txt from /Documents/Paradox Interactive/Stellaris/ if you have made any custom empires or races.
- "uninstall" in Steam-Stellaris
- unsubscribe from ALL mods in the Steam Workshop for this game
- manually delete both the Steam/SteamApps/common/Stellaris AND Documents/Paradox Interactive/Stellaris folders
In particular you need to make sure there are no files or folders left under either the Steam Stellaris or Documents Stellaris locations, before installing again.
- re-install game in Steam, run a Steam Verify when done.
- add stellaris.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game BEFORE restoring the user_empire_designs.txt file and save game files, and before subscribing back to any mods

Let me know if that improves matters!