Ive been having this problem in Counter Strike source where playermodels with jigglebones do this very fast “snapping” movements (like almost so fast its flashing). Ive tried playing with cl_jigglebone_cutoff, fps_max, turning Vsync off, and even playing with rates to no avial. They seem to work again at random mostly when there are few players left but sometimes not at all. Also setting different jigglebone code does not seem to work either since I tested like 20 different configurations. The models work fine in HLMV and in the player select screen.
Any suggestions or is this something specific to CS:S?