Hi!
First of all sorry for my bad english . When I'm using the rss plugin, in the sources tab if I check the checkbox "active" of any rss url, in ksysguard I can see that ktorrent takes %50-%60 of cpu usage. And if this checkbox is not activated ktorrent takes the usual %15-%19. It works without activing this, I mean, you can press the update button manually and you can download whatever the rss contains, but it is not so confortable.
This maybe isn't so annoying in a desktop computer that is better cooled than a laptop, but believe me, it's very annoying in my laptop because the continuous coolers sound.(my laptop:intel core 2 duo t7300 2GHz, 2GB Ram...)
I have Debian Lenny (testing) installed and it happens in ktorrent 2.2.2 installed via apt-get, and in the latest ktorrent 2.2.4 version, compiled from sources and installed with checkinstall.
If you need more information please tell me, I don't know what additional information include.

I will ask the RSS plugin author to take a look at it.