Here is the article on it and also more options you can load in the game as well. https://support.steampowered.com/kb_article.php?ref=1040-JWMT-2947
Using -HIGH should force the game to run on "High Priority" without using the worklist(?) (CTRL + ALT + DELETE or CTRL + SHIFT + ESC). -lowmemory and -nomansky can also help in some cases, but I am not certain they work well with UE4. I have used them for ages though.
So how about we get rid of all of the players, then the game will finally run like gold - simple and effective