Well we’re talking about porting, not emulating. So while there might theoretically be a few minor performance issues in the unlikely scenario anything like this actually happens, PS2 games theoretically shouldn’t be unplayable! Again, because it would be a port, so a good deal of the code would be re-written and optimized for the Vita. Look at the Sly Cooper, Jack and Daxter, and Ratchet and Clank collections! They’re all playable! There’s proof right there that PS2 games can be ported to the Vita and run mostly okay! Of course, this is all theoretically, as it’s very unlikely anyone in the would be willing to pretty much reverse engineer PS2 games to run on the Vita.