in my case X-Plane 10.45 worked very well on my brandnew pc in the beginning with a file-size of 320 GBs with heaps of plugins, z-sceneries, airports, tons of aircraft....etc. - Then all the sudden I got a frame-rate of 6-12 fps so X-Plane can't be used as a simulator any more.
We did benchmark-tests on the CPU, GPU, Motherboard, SSD-drive.....the result is that I got a working i7 4 GHZ processor, a very fast graphic-card, 32 GBs of RAM with a 8 GB VRAM......but I still can't getter a higher framerate, even with no plugins, sceneries, libraries or additional aircraft installed...just "naked" X-Plane 10.45 with a Cessna 172 and all rendering options turned down don't help the problem with an extremly slow frame-rate!
Reinstalling the operating-system (Windows 10 pro) and reinstalling X-Plane through the 8 DVDs and through download didn't solve the problem either. - Could it be that there is a bug in X-Plane??