The main thing that lags from time to time is running Firefox and the older Openoffice 1.1.5 (the odin based one), it seems that those apps like a faster processor. They do run, just a little slower then I'm used to.
The problem is not the processor speed (although that does have some effect), it is the amount of real memory. Those applications need a lot of memory to run, so they end up paging all of the time. That significantly slows everything, but they are still usable, as long as you stay away from complicated web sites, or large files.