I have built my game in server mode on Mac OS and attached profiler to it. In profiler I can see unreasonable high cpu load.
Other scripts take a lot of cpu time. How can this be optimized?

Vsync takes a lot of time otherwise. How can it be since I have disabled VSync, built as server, run with -nographics and even removed cameras and UI?

I dont know what your game is doing in terms of calculations from custom scripts, but if its not just an empty project, then i dont see why 33ms is unreasonable. Check your servers specs maybe? Also VSync just idles for a need amount of time to reach the fixed target FPS, meaning its not actually under load, even though the profiler is showing it as a big lump of color. Think of it more as headroom - how much processing you can still do per frame and have your target FPS.