This is a bit of an odd question, and I don't think 'laggy' is the right word, but bear with me.
I installed Ubuntu 12.04 some time ago after a windows crash on a desktop I use from time to time; more recently I upgraded (note upgraded) to 12.10. Overall I am happy, it's clean, fun, simple and it works.
I've been tinkering with it (12.10) a bit more lately, and then yesterday I put an old hard-drive into my computer and re-installed XP-Home on it (for particular reasons that only Windows can fulfill)--though Ubuntu will remain my main OS. I noticed while using XP today that in comparison, Ubuntu overall seems slower.
In XP when I double click, let's say, 'my documents' the window opens almost instantaneously. The same thing is true for media, video files are launched in VLC very quickly. I've been noticing that in Ubuntu there is a serious delay between clicking and opening. Enough that sometimes I double-double click because I think it's not going to open. Things always launch with no problem, but there is a definite 'slowness' to the way the whole OS runs.
I will note as well that programs, once they are open, run, respond, play and act completely normally. Videos are fine, web browsing is snappy, photo-editing is great, downloads are normal--it's just the actual OS that seems affected. And as well, there is not a lot set to open at start-up, and there doesn't need to be any load on memory or cpu whatsoever for this to happen.
I find this surprising because I wouldn't imagine this to be a hardware-derived issue, since I am sure Windows XP hogs more resources than 12.10. The computer is moderately new with 2gb of Ram and a few-years-old processor.
I guess my main question is--could this be a result of 'upgrading' rather than having done a complete wipe and fresh install of 12.10?
Are there any diagnostics/tests I can run to determine if something is wrong?
Sorry if this is convoluted, all help is appreciated.