If you are getting 4 FPS on maps then I seriously doubt the performance update will vastly improve this. Say it gives us 50% boost in speed (that is being very optimistic) you would then get a huge 6 fps instead of the 4 fps. No, to speed up any level that slow will mean removing entities in large quantities: or at least spreading them out a bit.
I see this update smoothing things out more. GG will struggle less with lots of entities as it's core can churn through them that much faster. Lua scripts should operate faster and so give faster AI performance. The best part of the update is the potential for other improvements now, faster terrain, occlusion, entity batching. These things will make a far bigger difference to overall speed.
As to improving speed here and now there are many options. Reduce the camera distance, the terrain size. Fiddle with the distance transition and range settings. Reduce the grass percentage as low as you can live with. Increase its width to help make up for the lower coverage. Turn off collision and physics for any entities the player will never reach. Keep your dynamic entities down to a minimum if you can.
If you can live with lowering the shaders quality, do so. It will give you more FPS than all the options above generally. Terrain is the killer. Try a test. Do a small scene and see the fps difference between all of them. You should find setting the terrain to medium or lowest will give you the best boost of all the options. Grass makes little difference at all on my machine, so I normally leave that on full. Entity quality makes a fair difference as well but of the options available, is still second to the terrain reduction. Don't forget you can turn off terrain and water etc when you do not need them. Big speed increases from those generally.
My compo entry Subterranean Secret runs fairly well on my machine through all the levels, as I have done my best to keep speed up with some of the above methods. I also broke it into several levels rather than one large one. GG just can't handle huge scenes very well yet.
Here's a video I made. If you want to check the game out it is available on the link from my Youtube page. If you do and like it give it a vote
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.