Have carried out a little more experimenting with this ROM and it woud seem that changing Radios is quite a good option certainly from a resources point of view.
I have changed mine to a vodafone 4.49.25.17 which you can find
here Now you may perceive this as a backwards step, maybe it is, however, I do seem to have more available ram than before and, editing contacts through Sense 2.5 is quicker, most notibly when tapping the 'Done' soft key. It's not instant, but it is on par with Sense 2.1 which was always way quicker than 2.5. Of course, this could well be a placebo effect but time will tell. If you choose to use this radio, do so at your own risk, you have been warned! (No, it won't over write your ROM, for those that don't know, if you don't know, then the question begs, what are you doing with this?)
I do have a couple of other issues which as far as I am aware are ROM and NOT Radio related. Essentially, I have to press either the hardware or soft key twice to come out of call history (only when viewing missed calls through notification manager)
and,
When my BT headset is connected, (Plantronics Voyager Pro) after dialing a second number, the softkeys in the dialer fail to make any sound when pressed, not even through the headset, but are fine when disconnected. Minor but annoying!