White lines across large maps in Firefox

Whenever I use maps that are larger than the default grid size it seems, they have white lines running across them, by the look of it where the normal grid would end. This repeats as long as the image is regardless of whether the normal grid is off or on. Here is a picture with grid off. You can see the lines that meet in the center of the page. One of my players sees this as well while the other two don't. Trying on my own, this doesn't seem to happen in Chrome but it does happen in Firefox.

Hi, Veovis . This is what the Dev Team has said about this behaviour : [...] this is due to how canvas stitches images together when zoomed out. Sorry for the inconvenience! To avoid viewing these lines, you migh twish to use Chrome, as you've noted. Alternatively, you might try splitting the image in half (using image editing software), and uploading the resultant files to replace the full image.

Just a thought but have you installed the newer Firefox which just came out? Suppsuvily it is totally rewritten and might make a difference.

I just switch to Firefox Quantum, and noticed the white line behavior. The gain in speed far outweighs the minor graphic glitch for me.

Still there even with Quantum. If there's any setting I can change to fix it I will, but I have found nothing so far. Thank you for the comments.