Gamers in the EU are used to getting the short end of the stick when it comes between them and the US, and now another inconvenience they will have to deal with is the fact that the recent PS2 games that have been added to the PS4 now playable thanks to emulation, are struggling to play on the system suffering from frame rate problems and stuttering often meanwhile in the US everything is fine and dandy.
The reason the region your system is in is effecting the performance of PS2 games is due to a difference in the version of the game for each region. For those in North America, the PS2 games are running off of NTSC code whereas those in Europe are running on PAL code which runs at a lower FPS than NTSC. To make up for the difference, the PAL version is being boosted using frame blending which while it does increase the FPS, it also makes stutters more frequent.
This is beyond frustrating as there is no way to play games via the discs we might already own as Sony want to make money off of this but the only problem with that is the PS2 games are way overpriced, plus there is no way to download pervious PS2 games bought via PSN on the PS4. Paying huge amounts of money for very old games and not getting the best product will leave a bad taste in EU gamers mouths. The best thing to do now is if your planning to buy any PS2 game is to head over to the US store and buy from there.