Don't take words literally. Instant in this context means what jawngee said, that it was so responsive to the degree that people conceived it as instant. Awesome. Layers were unlimited meaning you could add as many as you want. Undo operations were unlimited meaning you could work on it for 10 hours straight and undo to the point it was before you started working on it. I believe that's what everyone gets from these words, except you.

It's not like people will think it's unlimited for real, there's no such thing.

It seems to me you are having problems interpreting words in context.

EDIT: I mean, if he said you could have 8K undos, or 8K layers and the response time is <15ms would that make you feel better? Does it make a difference?

We write software for humans. The same humans who can't tell the difference between instantaneous events and events separated by less than a few milliseconds. The same humans who won't be around for long enough to recognize the difference between a really large number of events and an unlimited number of events.

So, by all means, continue to write software for those ideal beings that live in a world of comprehensible instantaneous and unlimited events, but you'll find that most people on this forum are operating under a different assumption.

Unlimited to the capacity of the resources of the system.

Meaning they did not hardcode limits, and I assume had a O(1) or O(n) type scaling.

It's just not a useful factor of the conversation if it is actually instant or if it was just so fast people felt it was instant. I could spend years getting the frame rate of one of my games from 59 to 60 per second, but it isn't a meaningful difference.

You are amazingly pedantic!