The first computer I ever used had a 56k modem, but I can empathise with greybeard stories about watching text appear one character at a time from 300 baud mode

The first computer I ever used had a 56k modem, but I can empathise with greybeard stories about watching text appear one character at a time from 300 baud modems because of the task-tracking software my employer uses. I load it up in a browser tab in the morning, and watch as the various tasks appear one at a time. It's an impediment to productivity. The rule I've come up with is one user action, one request, one response. By 'one response', I mean one HTTP response containing DOM data; if that response triggers further requests for CSS, images, fonts, or whatever, that's fine, but all the modifications to the DOM need to be in that first request.