Rockox very laggy on iPod 5.5

[mangoman]

Hey there, I just installed the RockboxOS and I'm having problems with GB/GBC-ROMs. They are
laggy as hell, even when i put the max frameskip up to twenty, it just skips 18-20 frames constantly according to the stats. i have tried a bunch of games including pokemon crystal version (which i've seen working on this device in various videos), super mario land or even tetris. any idea how i can improve the performance? thanks in advance!