Serious chug when using the Shiber's Brook map

I haven't experienced this with any other maps before, so I'm wondering if there's something unique about this particular map (or maybe how I'm using it). This is what I'm doing: Create a new Page.   Set the size to 30 x 45 Onto the background layer, drag the image of Shiber's Brook from Bogie into your map area (I found it when I searched for "town"). Change the size so that it's 2 wide and 3 tall. Position it in the top corner, then grab the diagonal and drag it so that it covers almost the entire map (I left one square of border all the way around it, but that doesn't seem to matter). Using right-click or your favourite pan method, pan the map around.  It's mostly smooth. Now add any token to the Object layer (I tried a couple of Devin Night townsfolk and one of Scott Helm's zombies). Now pan around the map.  Any time the Object is on screen, the framerate drops like crazy. I tried it out with a couple of other maps, like "Rustic Village Premade 1" and didn't have any trouble, plus I have a few other pages in a different campaign which have background layers composed of a bunch of different tiles and objects and they're not having trouble either. I'm using Chrome and Windows 8; I can add requested machine specs if you're not seeing the issue.

Okay... I guess my concern is that this map is available free from the Roll20 marketplace, so I sort of expected it to work properly :)  Is it possible to get a Roll20 friendly version of it in the marketplace?

Anyway, I downloaded the full version of the map, cut the size in half, converted it to jpg and uploaded it; now it works.  Thanks!

Hi Reed It looks like the problem with that map was a combination of it's size, and a transparency channel embedded in the PNG.  Because that was a free map that actually comes from an external source, we don't have any way to make the content creator fix the problem, so we've pulled it from the marketplace to prevent this from happening to anyone else. However, I ran the original file through Photoshop and resaved it as a lower resolution JPEG, and it seems to have taken care of them problems when I tested it. Feel free to grab this copy and use it instead.

Reed P. said: Anyway, I downloaded the full version of the map, cut the size in half, converted it to jpg and uploaded it; now it works.  Thanks! Looks like you already took care of it. glad it's working for you now.

Thanks Ken and Kristin for your quick and helpful replies!