Originally Posted by kovidgoyal
resizing window/chaging font size means the layout has to be redone. If you load books to the reader via the Connect software the laying out is pre done and cached in the reader's XML database. Also HTML is a much more complex markup language to layout than LRF.
Yes, more complex because of CSS support too.
Dividing the books into more files might be a solution to avoid a long waiting time on DE, but it also means that it'll take longer when you get from one chapter to another...