Engine: Possible stutter fix
For some time, I know we've been trying to figure out a way to resolve stuttering/frame pacing issues in Windows 10 (seems related to desktop composition, which gets disabled by eduke32 in Windows 7).
About a month ago, I tried to resolve this by calling dwmapi_DwmFlush() after calling SDL_GL_SwapWindow, and lo and behold, it worked very nicely. However, this has the effect of preventing the framerate from ever going above your refresh rate, regardless of the setting of r_maxfps.
I suggest giving this a try, and sending builds out to people experiencing frame stuttering, see if it works out.