Because past delays of about 100ms, users lose the sensation of directly manipulating the page. The feel of a page is part of it's aesthetic.

Also, immediate feedback reduces anxiety and mistakes (for example duplicate submissions).

https://www.researchgate.net/publication/391230228_Cognitive...

https://www.nngroup.com/articles/response-times-3-important-...

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gizzlon 2 days ago | parent [-]

Looked at the first one, and that's in a game setting? And they test 600 ms??

edit: The second one is more useful IMO. It's hard to get under 100 ms with a roundtrip, but < 300 ms should be doable, right? So you do lose the sense that you are directly manipulating data. In most cases I think that's a good trade-off. Exceptions would be things like Google docs, but that's also because it's a well made app I trust to actually sync my data without loss. Unlike most SPAs..

	▲	nfw2 a day ago \| parent [-]
		300ms for network latency both ways, with server potentially doing its own network calls for data to fulfill the request, interpolating the html, and then browser rerendering client seems like a stretch