Well, in my personal opinion, Tapatalk became worse and worse over the versions, now it just sucks ...
vdr-portal.de with the WBB is fast with all of my browsers.
I can't speak on Tapatalk because I don't use mobile devices for forums, but I can say this forum is very slow compared to the previous one when using my desktop workstation. Even if this forum is optimized for mobile now, it shouldn't be slow on desktops so I don't know what's up with that. No other forums I use have a problem and even the "old" vdr-portal didn't. It's only this new one.