I sent an e-mail to support with the Subject above, and an attached file. I believe something like this has been reported before, but I'm not sure it is exactly the same issue. Please, confirm that you received the e-mail.
I have received your e-mail. It does not really hang, it just takes a very long time to replace 40.000 occurrences in a 14MB file. We'll try to improve the performance.
Indeed, when I came back this morning it had finished. I've experienced this before, but it had never been this bad. It'd be really cool if you could make an improvement on this.