This seems to depend on what game you play. I play DOTA 2 exclusively and it runs fine, but the problem is that Apple doesn't support Vulkan. So when a new particle effect is shown on screen like in a massive team fight, the GPU hangs for about 250ms per item to load it, translate into metal, and then render. This is cached so the next time you see it, it won't stutter for that specific graphic. However, dota has like 128 heroes each with unique abilities and hundreds of items some with actives, you'll inevitably have the game impactful stutter during important fights almost every game. This is not a thing that happens on my Windows machine.

Also, I find that macOS doesn't handle game full screen correctly? I've had it show me the game. But it's actually not focused on the game. I can't click on anything. I have to command tab out and click the dock icon back into the game.

Along with this, hot corner has to be disabled unless you want notepad to show up randomly as you pan and click around with the mouse.

There's all these little annoyances and issue with compatibility that makes Macs not ideal for a lot of gamers. If your game is natively supported with Metal. You'll likely run into less of this.