See if changing rendering mode to multi-threaded improves things

[hhyyrylainen]

Currently the render mode is set to single-safe, though I think because of that we might have at least one crash: #2078

So I think we should try setting the render mode to multithreaded, if it improves performance that would be a plus as well. If it doesn't break anything, I think it would be worth it to change to it anyway.

[84634E1A607A]

I think it does improve things.

https://1drv.ms/u/s!AmQa4DeAoN8FlXnMeaXfpBmB5gnm?e=jDNssA

[84634E1A607A]

And I haven't found any issues yet.

[hhyyrylainen]

Thanks for testing.this
I made a PR to make it easier for other people to test this as well. On my computer I didn't notice any real FPS improvement, but I also don't think I experienced the jitter that the Godot editor tooltip warns is possible in multithreaded mode.

#2301