Reboot and try whether it helps. Period.

rebooting helps. The point is, I don't think I should have to reboot every couple of days for the phone to remain usable. Others on here have reported going weeks or months without problems.

i have another friend that i compare notes with and this is what we have discovered.

the point about 'going weeks or months without problems' depends very much on how heavy a user you are. my friend is a very light user. when i checked his swap usage and compared it to mine, mine was 6 times as heavy in swap usage as his. as a result, i found my phone to be more sluggish than his after 2 weeks of uptime.

rebooting every couple of days means you are a heavy user. by heavy user i mean you run a number of memory heavy apps (such as web) frequently. and 'frequently' means enough for swap space to be used quite a bit and become fragmented.

in my case, i am a very heavy user. microb and opera at least 6-10 times a day on separate ocassions. each time i'm done, i close those apps. x-term a couple of times, sms, phone, etc. all these add up to heavy swap usage.

i now have a script that runs at 5am to defragment the swap devices and my phone feels like it's after a fresh reboot even after 2 weeks of uptime with MY usage pattern.

the other thing to remember is: what is slow / sluggish to you?

since you have mentioned a reboot helps, i'm assuming the problem is due to swap fragmentation.

My N900 is fast (compared to a 1.4ghz Android phone), but every device, user, their installed apps and the pattern of usage is different.

Some devices respond well to speedpatch, some dont and some devices need a reboot every few days.

Thats just the way it is. The N900 is one of the fastest easiest devices to reboot so I dont know why people have such a problem doing it.

xterm > root > reboot. Done OR If you are clever like Droll write yourself a script!

My swap defrag script:
You need to create a second swap partition in order to use it
Adapt it to your needs and run it as a daily task at ~4am
with cron/alarmed/whatever

yes, you need 2 swap partitions to do it. in my case, i made a few tweaks that are different from Megaltariak's.

i stripe the swap usage across 2 partitions with equal priority. some say it doesn't make much difference and may slow the phone down because the internal emmc is already heavily loaded by disk io. i did some tests and found that in my case (with my n900 and the apps i installed plus the way i use it), striping the swap actually helps. phone is noticeably more responsive under heavy memory pressure.

secondly, i only defrag when total swap space written (not used) has reached around 600mb. taking into account the max default swap size is 768mb, 600mb is a pretty safe threshold.

but the solution above ignores all that and simply defrags everyday, which would also work. try it and see, you should notice a difference in the n900's responsiveness.

Great script.

Not wanting to hijack...but could you perhaps explain how to do this?

To create the swap partition , make a backup of your microSD data first, the easier way is to use gparted on a Linux pc and create a swap partition on the microSD, you can even do it from your N900 if you have easy debian installed in MyDocs (internal memory)

Save the script in /usr/sbin/swapdefrag

Then chmod it:
chmod a+x /usr/sbin/swapdefrag

Install alarmed and make a task running each day:
sudo swapdefrag
You can check the effect on memory and swap by checking the /tmp/swapdefrag file

don't forget to mount the swap partition at startup too.

http://wiki.maemo.org/Swap_on_microSD

but becareful, with swap on microsd, removing the back cover automatically unmounts the microsd and would cause the n900 to most likely reboot.