That could be it. Installed the DLC pack at the same time as the SS undub. Though I also noticed when I enter a battle with a new type of enemy I haven't fought in a while it will usually hang for a few seconds with the big X on the screen, presumably to load whatever assets it needs, and then subsequent encounters will start right away after that.
Not sure if that was always happening or not, may just be I started paying more attention because of the long delay I noticed starting up.
I can confirm that this issue exists in the original Japanese version as well.
it also happens on the untouched EUR release wich i've been playing till i get SS release.. btw is the Mega link release of the game working properly? i'm downloading that one to check it out since torrenting kills me