ISO games running slower compared to PKG installed games

I recently installed PS3Hen in my PlayStation 3 (Super Slim), and it works perfectly fine go the most part, but I noticed that in some games (specially Uncharted 3, Last of Us and GTAV) run and play worse when playing on ISO, for some reason. Now, I would go fully PKG installation as it seems to be more functional, but sadly not everything is PKG. Last of Us and Uncharted have Latin American dub, but the thing is I am not able to find a USA based PKG, so that makes it harder. Anyways, I don’t know if the issue comes from the ISOs or maybe the PS3? I have the latest firmware (4.92 I think?). If anyone knows something, please let me know!