Divide the watchlist in pages
The watchlist is just one page and with around 800 films let's say I could watch all those films before the page loads.
Why can't the watchlist have pages? Like 100 items in the 1st page, 100 on the 2nd and so on.
I had to create custom lists to serve as "new" watchlist because the watchlist is unusable. Yes I can hide tv shows or movies but the page is so heavy that my browser often crashes before it loads. And with around 800 films just hiding the tv show doesn't make the page lighter.
The reason it is currently one page is all the filters and sorting are applied client side in the browser. Pagination would break that. I'll have to think about this more and see if there is another alternative.
Not sure this helps, but there are direct links to "pre filter" your watchlist for a specific type of content.