This bug has been around for a while (not a 3.14 regression).

Some of the torrents I have take 20-30 seconds to select in the "All Torrents" tab. When I click on the torrent, ktorrent will freeze, and my CPU will go to 100% for a good 30 seconds or so, and then ktorrent returns and the torrent is selected. The only reason I can think of what might be causing the delay is that these torrents have thousands of files in them.

If you need some torrent examples, the torrents I'm experiencing this with are coming from http://www.pleasuredome.org.uk (not a porno site despite the domain name).

After logging in, click on the torrents tab, and select the [FREE] torrents. The one I currently have most problems with is:
[FREE] MAME v0.128 - Extras (Core)

You are right, this torrent is handled slowly, I will see what we can do about it.