tips on speeding up LR3?
no. I definately have 1:1 preview generated for the image. My problem is in the develop module and sluggishness there in further editing a heavily edited image.
One thing that may help you, is if you have a large number of (for example) clone or heal spots active, and they are slowing down the responsiveness of the other adjustments, you can temporarily disable them all using the toggle switch at the left side of the clone/heal panel. This will prevent them needing to be re-calculated and re-displayed every time Develop needs to update its preview. Same for local adjustment brushes (say, if you want to work on something else such as sharpening, or your crop, or whatever). This would just be a temporary workaround, as needed.
The main problem will remain, though. LR is excellent up to a certain point - what I describe as adjusting, without altering, the image - but if requirements go beyond that, at some point it does make more sense to push the image to a bitmap image editor. Especially if there's significant amounts of cloning or healing required. LR is not going to perform so well with dozens of live, parametric spot fixes all over the frame, on top of all the other things it is doing on-the-fly. Just too computation intensive, AFAICT.