Yes those effects can hit pretty hard on the FPS. But they are optionnals so CIG can choose to give (or not) options to turn them off/reduce them. Those options come in beta normally, not alpha. But CIG add some because we play the alpha.
Just keep in mind that for now, it's the old renderer and DX9 managing those effects, they can't be sent directly to the GPU. With Vulkan, they will be able to render them without calls to the main thread.
No, atm
the renderer use only ONE thread, whatever number of threads you have at disposal. That's why the more important thing
for now is to have the more power by thread unit because this
ONE thread with bottleneck you even if you have the best graphic card in the world and 50 threads. The GPU always wait for the CPU on powerful card. That's why the new renderer and Vulkan are important. CIG will get rid of this limitation.
The unknown part about the new renderer and Vulkan is "will CIG use the real power of Vulkan ?". If they only adapt DX9 calls for Vulkan, the gain will be limited. If they rewrite completly the calls to the Vulkan's specific functions and make a good work on parallelization, the gain will be significant.