I have used Process Lasso for several years now. I ran a quick benchmark with Steel Beasts. With my PL config, I was getting 42-48 fps in my benchmark scenario. With PL disabled and Win10 Game Mode enabled, I got 43-47 fps. Just three run throughs on both.
What I did find is that email and IM didn't update while Game Mode was enabled. With PL, I can get basically the same results, but have a lot more control over the priority of the apps and porcesses. Its a typical MS feature in that it comes years after third parties have already solved the issue and MS's solution isn't quite as functional.