Moving files to internal memory won't make that much of a difference, actually - you'd get more of a boost just by cutting back on files, for example the low-res fonts (font10 and font12), any dictionaries you're not using, audio files (back to just Basic/Core or even just Core), etc. If you do move files to internal memory, dictionaries (even small ones) generally contribute a bit more to loading time than other files so those are the first ones you'd want to move - fonts are a bit slower to load, too.