cl_showfps "1" show uncorrect framerate, to see fps correctly you need to use net_graph.
After update when i set max_fps to 100 game runs at 101 fps, 1 more than needed.

When you fixed this issue you actually achive opposite effect=)

so you need to do
Fix fps_max to actually run at that framerate, not 1 more.
then
Fix cl_showps to show actually framerate, not 1 less.

You can easilly verify it by using something like fraps.