Overall this seems as fast as it has been mostly. Some objects do seem to have issues still, tree02 being one culprit I have noticed for an age.
I find using the i tool as sparingly as possible will help keep FPS up and still generally work okay. Big clusters of trees all in one spot will slow things dramatically and quickly. Rule of thumb is don't overpopulate any spot if possible, obviously sometimes you have to, but if you try to be efficient from the start, you will get much bigger levels made.
I have just started putting a few tutorials up on my youtube channel. Just the one at the moment (the second is looking like it will take 7 hours to upload :0 ). There are several older ones and other related stuff there. It may be worth checking out.
https://www.youtube.com/user/RetroGamebloke
Not sure why you are getting such a huge difference in performance, unless it has perhaps defaulted at different settings than before? It could be the map of course. Sometimes you get problems moving from versions; I have had to bin many maps before now. Have you tried making a new test map to see if it performs better?
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.