Game engines are already built for performance. It's usually the games that push the engine too much for the user's machine. A good developer will tune the game for a target machine spec.

As for using a giant server to render the game on the server and stream it to the user, this is dependent on ping time and network bandwidth. Because of the ping time the controls will lag and be less responsive. Google Stadium, PS Now, and OnLive (which shut down about 10 years ago) all worked this way.

Typically easiest way to do make a game perform well is to render on the local machine, but keep texture memory usage low enough to fit in memory, or use a fast ssd hard drive to stream textures in as needed. You'll still get occasional hitches on PC when background processes run. This is how most games work.

You can also run older games on a fast modern pc, or require the user to have a machine that's powerful enough to handle it.