Indeed, I have about 2700 pages in my watchlist and I was affected by both bugs (the timeout when displaying Special:Watchlist and the timeout when attempting to delete a lot of items from the watchlist).
In the last few days, the display of Special:Watchlist stated to work, but very slow (about 15 to 50 seconds) with a message saying the changes over the last N seconds were not displayed due to the busy server.
When I first viewed Special:Watchlist today, it also worked slow (about 15 seconds), but refreshing the page was fast.