Building map as tiles in Roll20 vs. building outside as single image

I have some very cool tiles from 2-Minute Tabletop I want to use to build a dungeon.  There could be well over a hundred tiles in the file map.  How important is it in terms of performance to build the map outside of Roll20 (say, in GIMP) as a single image, vs. dropping the tiles directly into the map layer of Roll20?  

The more objects used in the game, the slower (lag) the game behaves. Consider having to track 1 or 10 or 50 tiles, which would impact the computer the most. Add to this that you might want to use dynamic lighting and other memory intensive features. It would be best to build the map outside Roll20 then just upload one image.

When you're talking about that many assets, it's better to build them outside.  Players with slower connections and/or computers will lag pretty badly just trying to look around.  I know this from experience; I tend to make really big maps.   The root of the problem is that Roll20 tracks the position, size, orientation, effects, etc. of every asset on the map all the time.  By building a detailed map inside the page you're requiring it to keep track of hundreds of them all the time, versus just a single image uploaded and used as a finished map.  If there are things you want to be able to interact with such as doors, chests, and the like it's fine to drop them in individually, but create most of the map outside of Roll20.

Thanks, that's what I suspected, but wanted to confirm.