I'd like to pick up the topic but in another context:
I'm currently building a dig&collect game ( pretty similar to Motherload if some can recall this classic hit ) and I'm using Physics to deal damage due to velocity at impact etc.
My ground is a tileset (currently 130x400, I'll change it to a max of 75x1000) with a physics and immovable behaviour assigned. If I dig and delete a tile however I get some 3-5 frame lag. I took a look into Debuging and I saw that the physics in the Profiler went up to 40-50% CPU usage for this time.
I don't know how the physics updater work but I guess it's lagging because it has to reevaluate the whole tileset or at least the whole visible screen. Is there a way to alter the update routine or do I have to use ghost tilemaps which are just about 75x25 or rather 25x25 in size? I haven't tested this ghost tilemap approach yet but I think this could help...
Best regards
Michael