I'm on a Windows laptop with a Core i7, 16 gb of ram and a dedicated GPU. Up until the 15.0.2 update there was some hitching and slowdown with these large files (and I noticed a weird bug where hitting T to use the Type tool doesn't actually change the tool) but now editing text can take up to 10 minutes with more than one file open. I can't make a screencast at the moment since I had to reinstall 15.0.1 to complete the project on time but the filesize we're talking about is 50-75mb, ~60 pages or so with about 300 linked images (it's a catalog).