On the menu of osu! the logo will beat to the beat of the song, at your constant framerate it's smooth, but when you open chat along with friends [F9] you lose frames and move down to 45 FPS (as if you've tabbed out). Along with that low FPS, if you leave the game and actually tab out, your frames get cut down to 15-20 FPS, making the osu! logo seizure for no reason.
http://youtu.be/cuDy2UK6btA for if the video doesnt work
osu! version: 20141031.2cuttingedge
http://youtu.be/cuDy2UK6btA for if the video doesnt work
osu! version: 20141031.2cuttingedge