Yeah, speed wise I'm doing fine on a 1ghz overclock. It could also be an issue of your memory card's speed.

For crashing, I found that my N900 was running out of memory awfully fast. If you do a `free`, you'll likely see that you have 3-4 megs free at most. To solve this, I ended up using gparted on a linux box to shrink my data partition on my mem card and added a swap partition. Once the swap partition is added, you can either add the swap partition to /etc/fstab, or run `swapon <partition dev name>`, and it'll stay till you reboot. Run `free` to test if it worked, you should see available swap space. That solved random crashing for me at any rate.