heelx suggested to watch time_step, so i found out that it had frequent jumps to almost the double value (0.2-0.4) wich was not the case on my laptop.

the cause may be some background processes with harddrive activity or the like.

so i played around a bit with time_smooth and for my case time_smooth = 0.666 works the best.
if i set it very high things get messed up in window mode, if its too low, its jerky in fullscreen.

so the holy grail, is 0.666 and not touching the fps_ statements. i would also suggest to set it in every 3dgs program. as you can expect that at least 1 out of 10 customers/players do have these time_step jumps for several unpredictable reasons.

what are your experiences? please share the knowledge.