Computer performs extremely slow while I'm in a loading screen of a game?

[F0cusX]

Recently I bought a completely new computer, the only things that I haven't replaced are the hard drive and PSU. The computer seems to be working perfectly except when I'm in any kind of loading screen.I'm using 2 monitors and while I'm entering a server or map my FPS drops significantly. If I have a youtube video opened on my second monitor it just spikes out and starts buffering, but as soon as I tab out of the game that's loading it loads fine. All of my drivers are up to date. Could it have something to do with Windows 10 (I was using Windows 7 before I got my new computer)? Or maybe because the monitors have different resolutions and refresh rates? Btw my specs are : GeForce GTX 1080 Ti, Intel i7-7700K 4.2GHz, 32GB of RAM, 850W PSU

 

[Carnaxus]

FPS drops are completely normal on loading screens, as the game is prioritizing code parsing over graphics rendering. I play Garry's Mod on my beast of a computer (especially compared to computers from when the game first released) and it locks up on launch for about five minutes every time because of how many files it's loading.