Reduce CPU usage of Headless mode

I run a Headless Mode Server on Linux(debian) and doing nothing. It eats about 5% cpu time. I have three question about that.

If I change the “Fixed Timestep” to 1 will fix this problem. What’s the bottleneck exactly?

And I found unity has create 28 background thread! How can I reduce that? I try to disable the sound. It reduce to 26…

How can I use profiler on headless mode?

Thank you.

Unity3D has a lot of threads in the background to handle a lot of things. Don’t ask why… It’s just how the engine manages itself. 5% is acceptable, because unless your machine is old, it’s really not going to make a dent in performance. If it was doing nothing and eating up around 80% of your CPU, you’d have to question what the heck was going on.

Headless may also use what’s known as a virtual framebuffer, as in, rather than using Xorg to pipe the 3D content to your GPU, it’s rendering to a memory buffer (which is being done on the CPU) and then being discarded.

I haven’t played with Unity’s headless mode myself, but I have a decent understanding of Linux knowledge. I’d be willing to bet it’s either overhead from the engine, or the virtual framebuffer.