I have the same problem, using 1.5, and that option you mention (macmanx) was the first thing I turned off…
After testing this a whole bunch (I’m re-categorizing posts, and therefore need to re-save them), I found that for posts with many links in them, the 5-minute+ problem occurs. When re-saving posts with only text or pictures (but no links), the posting is very quick as it should be.
I’ve removed all ping URLs in the update notification box, and it seems to help very slightly – but we’re talking about a 30 second difference here.
It’s almost as if even though the option to “notify any weblogs linked…” is not checked, WP 1.5 *still* thinks that it is, and does it anyways.
Does anyone have any other idea why this is happening? Or maybe a workaround? At 5+ minutes a post (btw, that’s a conservative estimate!), I’ll be re-categorizing for the next few months!