It's noticeable if something is moving because that won't look smooth. But a 80ms delay will be very hard to notice. An average reaction time is around 300ms.

With all the downvotes I'm getting I might be missing something though :P

You're not wrong about 80ms being a "small" amount of time, but you're saying that in absolute terms. Native UI tool kits for decades now have targeted <100ms latency[1]. That includes processing user input and rendering. 80ms for part of a render operation spends almost your whole budget.

The sum total of ignoring this kind of performance footgun is why apps like Slack feel so crappy. You can't get into the flow because it's a pile of high-latency, asynchronous interactions. I haven't used Photoshop in a long time, but back in the early 2000s even on my Compaq with 32MB of RAM it was snappy. I can't imagine using something as complex as Photoshop built as an Electron SPA and keeping my sanity.

[1] https://stackoverflow.com/questions/536300/what-is-the-short...

> An average reaction time is around 300ms.

just because human's reactions are slow, does not mean that humans do not notice. In music it's routine to have people complain when latency goes above 15 ms and it was recently shown that humans could notice in some physiological way down to half a millisecond of latency.

Do you have a source for the half a millisecond part?

Just curious