First bit of the solution. calculate your target sv_fps that you expect servers to use. now if you really do not want people zipping past static d's, invert your sv_fps to get the time for the maximum movement you want to allow. keeping players moving at or under this speed will allow the physics detection to work at your target sv_fps cleanly, provided you make the trigger zones on static d large enough to contain this maximum distance moved between physics frames. do not make it a direct dependence on the sv_fps though, if someone went and set it to 125 like they do in trick jumping, your players would be able to move at mach 5.