It's four times smaller, though, so enough to make a significant difference

800x600 was perfectly fine on my (family computer) 1997* era ATi Rage Pro 8MB AGP (funnily enough, it was slightly slower than the PCI version) card for Half Life 1. 1024x768 too but less FPS. Quake 3 Arena ran better.

I ran Half-Life at 400x300, because I didn't even had a 3D accelerator.

What?! Was I so privileged to have a 720p CRT at the time? (ok well not literally 720p, but a higher resolution 4:3... 800x600)

... actually remembering it, it was probably well after 1998, but I have plenty of memories going, "mmmm, 800x600". maybe even more at 1024x768.

I only really started to understand what it all meant and how neat better resolution was with Unreal Tournament, so... definitely post 1999