I often notice a lot of slowness when exiting the PSN Store on the PS4, presumably it's "closing" the app which slows down the rest of the system (though you can't manually close it like everything else). Still blows my mind that the PSN Store on the PC is by far the best way to access your content, and all the actual system stores range from bad to unusable.
And yeah, I get the delays when going into the TV/Video apps. They also rearrange the order of your installed stuff at random, so I'll get used to Twitch being two spots down then it'll change and I'll open Amazon by mistake or something.
I'm also getting occasional black screens on Twitch streams (until I close/reopen the app) and Youtube will randomly exit a livestream after an hour or so, but those are probably on the actual apps and not Sony. Just more shit that used to work fine.