You could overclock to 1100Mhz your not going to make HAM faster, especially if you have Devel enabled.

You really don't need to overclock for most thing's.
It's like having a V8 Mustang in a muddy field, you'll just wheel spin and dig holes, til you burn out the clutch.
If you wish to overclock you get better response if you use it on the autobahn (Games, watching Videos etc..).

Also bear in mind overclocking shortens your device life span and causes reduced battery life.

The best advise for a seemingly slow device is:
http://wiki.maemo.org/Reflash (Full Reflash, follow instructions)
http://wiki.maemo.org/Community_SSU (Install after reflash)
http://wiki.maemo.org/Kernel_Power (Install only the main app not the settings)
http://wiki.maemo.org/Swappolube (use recommended settings)
Put swap on uSD
Don't enable Devel in HAM
Keep your Widgets on the desktop to a minimum.

FYI this and more is already covered in great detail in posts and wiki's.