Background map disappears if I zoom in...?

Basically what the thread title says - I'm working on a fairly large map (64x40 squares with .5 grid size, two separate map images placed side by side) and whenever I zoom in to 80+% zoom the background map disappears completely, leaving nothing but a blank white slate with a grid and player tokens on it. This happens both in regular view and in gm-as-player view. The problem seems to be Chrome-specific, Firefox works fine in all zoom distances. I'm currently using Chrome 27.0.1453.116 m. In case anyone wants to take a look at it the map in question is called "The Hook", and is the page the player's flag is currently on.

Please send me a join link.  - Gauss

Link sent!

What are the image sizes and types (jpg, png etc)? I am guessing they are pngs? - Gauss

Both images are .jpeg, the left image is 3,96 MB and the right one is 4.6 MB. Both have a resolution of 6400x8000.

I made a new page with the same maps, but I scaled the resolution down to 3200x4000 while trying to maintain the quality so the images are about the same size. The same zoom-thing happens again, so I'm thinking the problem might be related to file size...? Not sure if it's related, but the original files are .PNG and approximately 50-60 MB each.

What DPI are you using for your images? - Gauss

...799...

Yup, there's the problem! :) It is giving your computer a fit trying to process that much information. What is probably happening is that your computer is running out of video memory and so will not process the second map image. - Gauss

Scaled the images down to 200 dpi and that did the trick! Chrome is still a bit slower while scrolling on that map though - is it strange that Firefox handles the map fine at high dpi and Chrome still struggles at 200?

I suggest scaling it down to 100 dpi, it really wont make a difference between 100 and 200 dpi.  - Gauss