What the heck is wrong with this room?

[Leo Graywacz]

When I created this roomful of cabinets it worked fine. But now that I have let it sit in my computer for a couple of weeks I needed to work on it again. I pulled up the file and it loaded normally. Then I needed to edit the hutch cabinet assembly. I loaded it into the cab editor and it took forever to load. The I reduced the size of the lower cabinet to 18". Again about 5 minutes passed before it came back. All the cabinets act this way. I added a bookcase on top of the countertop but I haven't checked how that operated.

Why is this room acting so slow. All my other files operate normally, just this room.