Here's a community announcement: If your game is stuttering it
may be due to something called
Nvidia Threaded Optimisation. See
this Stack Overflow thread for an analysis and solution of the issue. The easier way to fix it is to register an Nvidia profile that disables the optimisation in an installer. The key triggers of this problem for me seemed to be Nvidia Card, OpenGL, Multiple Threads, and FBOs.
There are discussions of this in other threads, but I thought I'd make one focusing on this exact issue. I hope some future SFMLer finds this before tearing all their hair out like I've done. It plagued me for years!