I've never heard that Linux in general, and Ubuntu in particular, was
"much faster" than XP but I've never measured it. The difference is in
terms of stability and safety in computing.

In my experience there isn't any big difference in "smoothness"
either, as long as both Operating Systems are running properly.
However, with minimal intervention Linux runs smoothly, while XP needs
anti-virus, defragmentation and anti-spyware, plus "Patch Tuesday" bug
fixes to avoid calamitous problems...

It sounds to me like you find XP better suited to your needs so why
keep beating yourself up with Linux?