Simply telling us that you are experiencing "lag" is very unhelpful. "Lag" could be used to describe one of many possible symptoms, each having many different possible causes. Here are some of the different kinds of lag you might encounter:
-You can get higher FPS by having a fullscreen window open behind osu! when you're playing in windowed. Running the game in full-screen will also increase FPS usually.
-Certain resolutions automatically set the game up to use High Definition textures. Set LowResolution to 1 in the config to force the game to use the normal resolution textures for any resolution. Do this by turning off osu! and opening your .cfg file with a text editor. It will be the name of your computer in your osu! folder. Save changes.
Please discuss any issues related to any kind of lag in this topic.
- The game's behaviour (either audio, video, or both) is delayed from realtime.
This could be a result of input lag--your mouse's actions are delayed. Possibly there are too many devices on your USB channel? If the lag is system-global, this is probably the case.
It could also be a result of output lag. Check that your video isn't set to prerender too many frames, and that there aren't too many filters, splitters, etc. between your PC and your monitor. Also, some HDTVs add a frame lag to perform dejuddering and such. Make sure any such filters are turned off. - The game's performance is choppy.
This might simply be a result of low machine specs. Go into options and enable the FPS counter. If it's a value below 60 and the frame limiter is off, your graphics card might not be powerful enough to handle the game. Also check that other 3d apps in the background aren't eating up some of your precious graphics performance. If this is not enough, try checking the Low End PC option. DO NOT try switching to OpenGL to improve performance! At present, osu!'s OpenGL engine is neither as optimized nor as feature-rich as the Direct3D renderer. It is there for compatability reasons. - Occasional momentary freezeups.
Check if another background process is monopolizing your system for brief moments. This could be caused by other games, web browsers, or server apps (including file sharing/torrents). Close all other background programs and tray icons and see if the problem persists. - FPS drops sharply after an update.
This is known to happen to some users after some updates. Restart your PC to fix it in 99% of cases.
-You can get higher FPS by having a fullscreen window open behind osu! when you're playing in windowed. Running the game in full-screen will also increase FPS usually.
-Certain resolutions automatically set the game up to use High Definition textures. Set LowResolution to 1 in the config to force the game to use the normal resolution textures for any resolution. Do this by turning off osu! and opening your .cfg file with a text editor. It will be the name of your computer in your osu! folder. Save changes.
Please discuss any issues related to any kind of lag in this topic.