Illustrator very slow when using not so complicated pattern

so I have a pretty decent computer as you can see below. Before it was good but I wanted awesome. So I upgraded my Video card and went all the way up to 32g of Ram.

Guess what? now it's worse than before!!!! When I use not so complicated pattern it's very slow and even freezes (and screen turns watershed white and say does not respond for like 20 seconds).

I use an official Illustrator version so it can't come from here. I updated my graphic board, Windows and Illustartor.

How can I make my computer use all its ressources on Illustrator? Because of course when I'm using Illustrator I'm not using anything esle.

Here is my components 
Intel Core i7-7700 CPU @3.60GHZ, 4 cores 8 Threads
32Go RAM DIMM 2400 mhz
NVIDIA GeForce GTX 1660
SSD Harddrive

See below the Benchmark test and task manager when my computer freezes using Illustrator

Please help

Thanks