I've been having this problem for quite a while (since launch, actually) and wanted to know if anyone else has too.
This happens whether I play quick match or ranked. Right after I choose my character, the screen will temporarily freeze for a while. Sometimes it is instantly after press "Start Game" on character select, and sometimes it waits until I get to the "Searching for opponents" screen to freeze.
The only time it stops freezing is when the game switches to the "connecting" screen, but most of the time, it just ends up going back to the "Searching for opponents" screen, where the game will freeze again. This loop goes on over and over, until I finally connect to someone and get into a match. Sometimes I just let the Vita sit there for a while until I see that I've gotten into a match, but most of the time, the game freezes for so long that the Vita will automatically go to sleep.
This is extremely annoying; it happens maybe 7 out of every 10 times I boot up PSASBR on Vita. I've tried restarting the app and restarting the Vita itself; nothing helps. Sony Santa Monica or Bluepoint, if you're reading this, please fix this asap.