I'll be honest I've run both OpenOffice and Libre Office and I'm not impressed with their speed/resource consumption both of them lag on my laptop and I don't think it's because of my hardware, for example Kile a Latex development environment based on Kate runs better although it's doing, I think more stuff in the background.
So is there another office suite/ word processor for a Kubuntu 12.10 installation, going with Kate seems too low end while doing everything in Kile is bringing in the big guns to early.
I am mainly interested in speed and of course saving in a reasonably used format, not in having a lot of bells and whistles.
There is abiword if you want a lightweight word processor. Others like Calligra are also available. By typing "Word processor" in the Software Center you should find many more:
It's not for everyone, but you can consider going web-based. Google Drive (formerly google docs) works for me, especially the quick-edit on my laptop. It has the added benifit of not leaving my files on my laptop, which is at risk of being left in the train, stolen, and stuff like that.
Obligatory, but probably superfluous link: https://drive.google.com/