I did a Search and added a few hundred files. They seem to trickle in a handful at a time as I delete ones I don't want. Then I have to resort and cull some more. I had assumed this was new behavior because I don't remember having this problem in the past, but I haven't added a lot of files from a search in months, so I may be mistaken.
Yeah this probably isn't page loading. What is new is that when you add downloads they go into the download list DB first and are then displayed. If the download DB is slow then I imagine adding files will be slow. For example if you're downloading at the same time you're trying to add new files you might just be hitting a disk bottleneck. You could try hitting the main pause button to pause the download and then try adding to the download list and see what happens.