I'm having a quick whizz through the contacts list, merging some ones that seem to have become separate. When I tap on a contact to see the detail then try to call up the top menu it takes about 20 seconds to appear.. What is the phone doing before it draws this menu? The slowness of this thing frustrates me generally, but rending a 7 button menu shouldnt take that long..

Good rule of thumb: THe more detail you give about everything you have installed, running in the background (which you may or may not know everything running in the background, hence it's a good idea to give a list of everything installed for really detailed troubleshooting), and whatever else you have launched at the time, what widgets you have, etc; the more we can help you.

(I get no such lag, and I have quite a large amount of stuff installed from devel, so it's probably very dependent on background processes, RAM use, swapping behavior, etc...)

Are you overclocked?
Are you using swappolube?
Long uptime? Tried rebooting?

Have you got conky installed?
If so what is eating the most cpu and memory?

Have you got battery graph installed?
What are your graphs like?

Htop installed?
What does it output? What's waking the cpu alot?

Quite a vague description of your problem if I'm honest, not much to go on.

I did a top, and there's nothing much beyond normal; I only just flashed a new copy of nokia's kernel (power kernel screwed up) onto this thing, and I havent bothered to cusomtize it much with apps ever. I left top running, hit the button for the menu in addressbook, and flicked back to see top.. osso-addressbook is consuming masses of cpu while it's trying to draw the menu, but I'm not sure how to go about finding the problem..

How many contacts have you got?
I have over 1k contacts and address book and the main menu from with address book are pretty much instant.

Are you signed in to any IM services?

No overclocked, No swappolube, just rebooted, no conky, osso-addressbook when it's trying to draw the menu but cpu about 8% when it's idle (hildon desktop and xorg -logfile), no battery graph/htop (should i get it?)

320 contacts, not signed into any services, no data connection.. can anyone suggest any tools I can use to diagnose cos i'm conscious that I'm not being very helpful! SHould I be backing up. reflashing everything and starting again?

I have over 700 contacts, almost all with images, synced with Hermes and Outlook.... And most have IM enabled. Mine takes about 2 seconds to load up. Something is clearly not right with your setup.

Maybe try disabling IM and/or seeing what plugins are enabled? Do you have a way to sync the contact list out somewhere (like to Outlook?). If so, you could do that, nuke the local contact db, and re-sync them all back in. Assuming maybe the db is corrupt in some way?

Guess you'll have to run osso-addressbook in terminal and have a look at what it's telling you (guess it will in case of trouble). You can post in somewhere like http://pastebin.com/ and post a link to that here

Flashing should be your last resort if your problem can't be figured out..