In Polygon, if you go to a contest, this link is almost unusable:

Specifically, I mean the "English (from working copies)". If you have a typical ICPC-style contest with 12 or so problems, it will almost always load for a really long time until I am eventually served with a CloudFlare "timeout" screen. (The one from packages works fine, but sometimes you want to see how the whole contest looks without committing your changes or packaging.)

My suggestion is, if there is truly that much work to do for the server, then run this PDF generation in some sort of background thread and show the user a progress bar.