I clicked settings->preferences and it took a while to load the preferences. I didn't time it. In my brain, it felt like 30 seconds, but could have been only 10. (Sorrry, I'm not a good tester) Then I closed it to see if it would still take a long time on the second try. The second time only takes 3 seconds. That seems slow to me. I checked on my other machine that has 12 and the preferences practically loads instantly. (not instant but I would never be able to accurately time it with stop watch)
if it makes a difference, the slow 13 has a lot of tabs open in both listers, but the 12 only has "this computer" open in each lister(so 2 tabs total).
I didn't understand what you meant when I read your question. So I just tried agian and noticed it opened the thumbnail page we were talking about on other discussion. That page did load instantly. I'm sorry but I don't know what page it was opening to before. I didn't realize it saved that. I don't know if it was the default page or the page I used last with version 12.
I will try a few other pages
Edit: I just reread that. I think I need to edit that, but I think it's better if I test the problem instead.
Edit: I quickly tried a bunch. Some seemed a little snappier than others but all were as fast as I expected. Sorry, I have no idea what page it was on when it was slow.