Thanks that's an excellent point Kristin. Sarah, Metroknight - thanks for the advice. I've been using jpgs rather than png or anything like that, and compressing any map I download using GIMP if it's larger than 1MB to begin with. Generally I can use a good 40% quality setting before any noticable quality degradation creeps in (in my experience so far this results in a file about a tenth the size of the original unless that was already compressed) . So I'm probably ok, and I certainly haven't noticed any issues so far as I said. Tricky with the built in art search - you really have no idea how big they'll be before you drag them across. Fortunately of course, searched artwork doesn't count for my quota but clearly could affect performance so i'll watch out for that. Have I missed an easy way to get the size from a search return (from the 'on the web' listings rather than my own uploaded library I mean)? In any case, it was all smooth enough while I was demoing to my group this evening with a player account acting in one browser on the TV screen, and my laptop screen running a GM account* so I could show them fog of war, handouts, access rights in action and so on. They were mightily impressed with the product, by the way. So anyway, I'm not overly concerned, was just curious to see if there were any known issues (e.g. "when you get to 50 sheets it doesn't matter how lightly populated the sheets are it all gets a bit iffy") - but thank you all very much for your replies. * i.e. both sessions were running on the same low power laptop, one in chrome, one in firefox, along with an IE session with all my other online game resources, a couple of PDFs and all my various campaign note documents and spreadsheets - Laptop handled it all surprisingly well, but then I only have 6 pages at the moment, at least two of which are mostly empty apart from some pre-defined tokens ready for copy/pasting and a few reusable scenery pieces for quick fire random encounter copy/pasting. The hardest part about running two sessions on the one device was figuring out how to turn off video and sound so my poor laptop didn't get confused! Everything else was sweet.