Yeah I get that same GPU crash all the time too - since 5.0 - the only way I’ve found to get around it is to optimize everything down to a point where it doesn’t happen - I have a 3070 (I’ve noticed it only seems to happen on RTX30 series cards) - I switch down to “Medium” scalability, just turn up GI to High sometimes to test (but that usually ends in a GPU crash).
But it sounds like you have something else going on to make it so slow - do you have multiple monitors?
One developer said his UE5.0 would run like a dog while he had YouTube open in a browser tab - closing that sped it back up again…
what results do you get from entering “stat gpu” in the console?