At least I think it's caused by ed2k, since it never happened when I ran for ages with just G2 and G1 enabled.
After about 2 days of being continuously connected to one ed2k server (and a changing mix of G1 and G2 hubs) the UI was sluggish, no uploads or downloads were occurring, few downloads were queued, and the network tab was full of red lines, some saying "network core overloaded". This with the D #: U # numbers both below 1kb/s so there's no way anything should actually have been overloaded; it was using virtually no bandwidth. Timers on the network tab were not counting nor were the bandwidth numbers updating themselves, though the log area was generating new entries, mostly about dropped connections. Oh, and the thing was using 100% CPU.
I closed it, but there's still a Shareaza process using most of the CPU after half an hour.
What the f*@! happened?
Version is 2.5.2.0, which I'd thought was supposed to be stable.