There is a lot of reasons, mostly: font rendering, unicode handling, all effects, while pure text is simply copying memory areas and nothing more.
full answer: https://unix.stackexchange.com/questions/41225/can-a-termina...
You only need to be as fast as one screen refresh
period, 1/60th of a second usually, plenty of
cycles on modern cpus. Many games that are very
complex graphically do it without problem
Rendering 60fps (or even 1,000fps) is not remotely the same as achieving low latency.
Even if a game is rendering at 60fps, input latency (the time between a user clicking a button and something happening on the screen) is often over 100ms.
This article breaks it down... there's a link to it in the original story about terminal latency posted by OP:
http://renderingpipeline.com/2013/09/measuring-input-latency...
Your reply also reads like games are getting away with introducing 100s of milliseconds of additional latency, which just isn't the case for the most part. There is hardware and kernel buffering that userland software can do little about, admittedly, that can easily add up to getting you above 100ms as you say. Even there, some improvements can be made:
Gsync reduces latency by getting rendered frames displayed as quickly as possible, by tying refresh rates to frame rates. "Time warp" reprojects rendered scenes shortly before refresh to help reduce latency between head movements and screen movements in VR - but this is also effectively "improving" throughput and worst case latency, by ensuring there's always a new head-rotated frame - even if the main scene renderer wasn't able to provide a full scene update yet. There's some talk of going back to single buffering and chasing the beam, although I'm skeptical if that'll actually happen for anything but the most niche applications.
Moreover, text mode display hardware does not absolve one of Unicode handling.