I think I remember reading that thread. I'll have another look.

At this point, what I really need are "quick" fixes to get frame rates down to an acceptable level. In other words, I don't want to rebuild my entire level again (which I've already done), but it sounds like I could maybe just copy all my blocks and textures, etc, out of each seperate level file, then copy them all into the same level file, and either see how they compile as one level (barring the stuff like plants sprites, windows, etc), and/or then re-chunk the level into a grid as you suggested earlier. But I really wanted to get the architecture all the way built before I start messing around with optimization, so I'll be doing that stuff later. You got me back on track though with the objects error I was getting, so thanks again for that!