The only time autosave is a PITA to me is when it's doing it on a network drive and locks up for 30 seconds.
This isn't about autosaves per se, but Altium's implementation, which I think saves a temporary ".$$$" copy in the project folder (i.e., on the network), then saves the recovery copy, and probably some other inefficient steps along with that, like modifying supporting files (project, structure, lock, history, etc.).
It probably doesn't help that the network involved is pathologically slow (I think around 20kB/s), but yeah.
On the upside, Altium's saving feature is so thoroughly prioritized* that I've only ever lost ~hours of progress, in over half a decade of using it. The single worst case was when the recovery copies weren't saving, which I didn't notice (because, hey, no one-second pause every ten minutes interrupting my work, right?), until I went to look and saw the last autosave was an hour or two behind..
*No doubt, they've had enough complaints from customers about crashes from other things, that they just can't be arsed to fix, that they hardened the save action instead.
Tim