Last night and this morning I was getting very frustrated with things being slow. task switching was stalling during annimations etc. i closed all apps and restarted just the browser and things got better for a bit.
but this morning I chose to reboot. and things are back to being super snappy.

i checked before reboot and my uptime was a little over 4 days. and I've pushed it hard in that time.

Ihave no problem just rebooting every so often to keep things quick. but I wondered if anyone else had witnessed this and if there are any thoughts as to what specifically might be at fault.

I saw something like it which I identified as being down to excessive memory use by, ironically, the system load applet.

(I identified this by using top from the xtern and hittimg m to sort by memory use)

I remember reading this has been addressed in the latest version of that, btw.

Since then I haven't had it back, but I do tend to close apps when I'm done.

If you get it again I'd recommend taking a look at top or dumping the processlist out to a file to try and see what's going on.

I did look at top, and didn't see anything obviously untoward. my surprise is that I was regularly shutting down all my open apps. It just seemed that something was maybe leaking memory or some such that meant it slowly degraded over time.
I suppose it could be a widget, one of those behaving badly would still have been running.

I've seen the super-lag behavior you are describing maybe three times. Each time it was immediately after rebooting, so for me it hasn't been "over time". The way to identify this particular buggy state is that the transition animations are extremely slow and sometimes I even see "shadow images" of the partially faded-out dashboard that "hangs" on top of the regular desktop icons.

A reboot has fixed it every time.

Despite what anyone says about Linux being an OS you "never have to reboot", the reality is far from that.

There are simply too many variables and too much software in constant flux. I am sure it will be something specific causing problems, I might even suggest the web browser (I always find Firefox on desktop Linux to gradually degrade if I leave it running for days). I think overall, the software the end user interacts with is never quite up for the challenge of being running 24/7. The basic OS itself is, as can be identified by Linux servers running for months, but once graphics enter the equation all bets are off it seems.

That said I doubt its half as bad as Windows Mobile. I never left anything running on my Xperia X1 as it was terrible even using it for very basic purposes. I expect the N900 to kick its *** big time.