Hey guys…
i was curious if anyone has run into an issue where unreal will slow down to a crawl…like everything view port, blue print window, material creation…etc…
it will last for a few seconds to a couple minutes and then all of a sudden go back to normal…this happens intermittently…i thought it was my pc but unreal is the only program i experience these issues.
any help would be greatly appreciated 
PC specs
Intel i7-5820K 3.3Ghz
16 Gigs of Ram
GTX 980
Maybe it is texture thrashing where the VRAM is almost full and therefore, directx constantly swap the texture from GPU <-> CPU - and this is what causing FPS suddenly crawl… like < 5PFS…
I have noticed that having a Slate dialog up caused a significant slowdown in 4.18 and 4.18.1…
I think it may have been fixed in 4.18.2.
Make sure you close any dialog (such as in the lower right corner).
If all other windows are closed, editor fps seems fine.
looks like it was all on my end…lol…apparently Nvida game overlay was causing my engine to slow down
Been having the same issues since 4.18 but it is also effect old versions of the engines as well. Disabling Nvida game overlay only saves a few frames about the equivalent of having a single extra popup window open.