It's been a while since I've updated this project, but I finally got around to moving the site to cheaper and faster hosting. It should now be more stable, render faster, and hopefully cost me less money.
I also added a new option to simplify gerber regions - in some files I've received from people regions were used for very high-resolution rounded rectangles, which made rendering take quite long. The "simplify regions" option can now be used to create a bounding box around regions, which is much faster, but might have some unintended consequences if your software uses regions for some other use. If anyone tries this out and finds issues with it, let me know/!