Do you have an SSD in your system? 10GB is a lot of data, especially if it’s a gazillion small files. You could also try to monitor RAM usage, at certain point in development the system will no longer be comfortable with just 16GB. The editor is relatively memory hungry.
Hello. My problem is a little bit weird cuz sometime when i’m trying to preview something from my content browser it cause huge PC lag (no matter what i’m trying to open, texture, material, mesh etc.) it happens pretty often and i can’t even move my cursor in this time. It takes like 3 min to fix and then everything works fine. My project folder is 10GB+ if it matter. Almost used to it, engine version didn’t matter, tried 4.15, 4,16, 4,17 (now).
Thanks for reading and sorry for my grammar.
If it’s not common issue it is probably my system. I’m using an old HDD and only 8GB of RAM so you are probably right. Well, at least it’s lagging only sometimes and only when i touch something for first time in session. Thanks for answer 
In this case I’d blame your system. A small SSD and another 8GB would improve the quality of your life by an order of magnitude!
Please consider marking this issue as resolved for now.
I have the same problem, I use a macbook m2 max. I just installed UE5