I noticed back in the DOS gaming era that DOS games ran slowly in hi-res modes. I was surprised to discover that this could be true on a modern machine.
I booted a 2017 i5 7200u (I think) laptop into FreeDOS and loaded Quake; predictably no sound but otherwise okay. However, in 1280x1024, it ran slowly, which seemed impossible.
I was aware that the processor has to switch between real and protected mode quite a bit, but I doubt that's the problem because I created a virtual machine, running on the CPU, and got Quake to run well in that resolution.
So, what is the bottleneck? The graphics chip? The CSM?