I had the same problem and it turned out my CPU was performing under because of malwares, but poorly implemented driver can cause the same ( Razer Synapse, Killer Networks ).
Maybe my post will help you.
Also note that there are reports about performance issues in the latest Windows build(also affecting other games ex.: BF,Dota,CSGO ) because Microsoft besides the new features (which also can effect performance) started to update Intel microcode to patch the Spectre and Meltdown bugs. However the performance hit on Windows 10 and newer CPU architectures (>=Skylake) are less significant, it’s still measurable.
Furthermore modems,gateways with Intel Puma SoC are also showing TCP,UDP packet loss(causing game stuttering) besides DoS vulnerability in their firmwares.
Upcoming updates probably will affect gaming performance as well but my guess is that users will notice just a few FPS drops. Serious FPS drops most of the time are faulty hardware, buggy software related on the client side.