Not sure which of the latest 3 or 4 updates has done it, but it's really wrecked FPSECE for me :/
I only have two games on my phone (tiny SD card), but they used to work pretty well.
As of the latest few updates, i've pretty much only had problems with it.
Game 1: Final Fantasy 8
Ok, there's alot of issues with this game
but most of them have been dealt with and it was playing pretty well a few version numbers ago. For some odd reason, sound goes away when videos run - but return once you get back into "play" mode.
Game 2: Harvest Moon: Back to Nature
This game wont run at all anymore, used to run (allthough with some slowdowns at times) pretty well.
All this game does when booted up is show the Sony logo, and then stop there - nothing else happens.
I've tried tweaking with the settings, uninstalling - clearing caché - redownloading and installing and all sorts of thing to get it working like it used to. No luck, I should try with some more games to see if it just aint' working perfectly on my phone anymore.
Edit: just tested with Final Fantasy Tactics - that one runs pretty well at 59fps (though even with the improved sound emulation, it still sounds like it slows down the music a bit?) - so I can play games
just not all the ones I used to be able to play. I dont have any other games to test
as most of my PSX games were sold decades ago.