1. Summary: My game starts to lag after I've been playing for a while, even though the FPS stays the same.
2. Type of lag: The game experiences typical low frame rate performance, resulting in unsmooth note movement that becomes increasingly noticeable over time.
3. My hardware/system:
   
   1. GPU: GTX 4090
   2. CPU: AMD Ryzen 7 7800X3D
   3. Double Screen, screen 1: 5120x1440 @240hz; screen 2: 2k @144hz
   4. System: Windows 10
4. OSU settings may be related:
   
   1. Fullscreen
   2. Frame limit: Unlimited (Optimal mode didn't work well with my high refresh rates monitors)
   3. Game mode: Taiko (I only play taiko, haven't tried if it happens in other modes)
   4. Skin: Default skin with some modifications (replaced certain effect assets with transparent PNGs)
5. Some observations of the issue:
   
   1. In-game FPS remains consistent, typically between 2000 - 4000.
   2. The issue occurs exclusively in-game, not during song selection or elsewhere.
   3. Restarting OSU resolves the issue temporarily.
   4. Lag gradually returns after a random duration (5-30 minutes).
6. Assumptions: Possible correlation with garbage collection due to Unlimited framerate.
7. What I've tried to resolve the problem:
   
   1. Tried Optimal framerate mode (resulted in a 60Hz-like experience despite a stable 960fps cap).
   2. Complete uninstallation and reinstallation of OSU.
   3. Play on my 144hz monitor
   4. Unplug my 144hz monitor
   5. Use default skin
   6. Use both fullscreen Window mode
   7. Adjusted the priority of the Osu!.exe process.
   8. Moved OSU installation to another SSD drive.

Blushing wrote:

Have you checked the performance troubleshooting wiki to see if it helps at all?

Make sure that you have nothing but osu! open and running.

wiki/en/Performance_troubleshooting

Naywils wrote:

I've had this for around 2 years and never figured a way of fixing it. Its the reason I don't really play anymore. Plays fine then after a bit the screen feels like its ghosting all of a sudden and feels laggy. Imagine playing at 144hz then randomly it feels like 30hz, thats what its like.