Shouldn't be too surprising. They just did various timing changes in 223, while fixing various issues (The Kingdom Hearts 1 eye freeze bug, a hang in Shadow Hearts, and I'm sure others).
I'd imagine it'd take a bit of tweaking and optimization before the changes settle down a bit.
and, for reference, you can see the change notes on revisions from here:
SourceForge.net Repository - [pcsx2] Revision 223