Having Gauss join the game might help rule out a campaign-wide issue. Based on her console log, it looks like you have a pretty complicated campaign going with lots of big image files. Is she using an older computer by any chance? Be sure to archive any pages which you aren't actively using, as that will speed things up a lot since Roll20 won't load the image assets for archived pages. Can she do everything else correctly? (E.g. pan around the map, when you switch the player bookmark to a different page she changes pages correctly, etc.?) My guess is that this is an issue with her specific computer rather than a Roll20-wide issue.