I just came back to the site, new browser, -new computer-, Google chrome browser. I was hopeful that performance problems with the game in the past were an artifact of a slower, older machine running flash or whatever. Nope.
I was able to get into the map, but when I try to load the level I get the following screen, which it never proceeds beyond. This is the second level that had this issue (the first one responded after multiple page refreshes).
Edit: Just as before, it does seem to respond after some page refreshing.