eh? that's really strange. So it's a connection issue? Because there aren't any additional files or resources to download and most of them are cached anyway.
I've managed to repeat the issue
I closed my browser (Win 11 Vivaldi - chrome based)
Re-opened - waited for all previous tabs to load
Opened up snap.berkeley.edu - wait till loaded in
Clicked on run snap - took 13 seconds before the editor loaded!
[edit] - tried doing same in Chrome and Edge - the site loaded quickly