If anyone was curious about why pcsx rearmed hasn't been improved much if at all since it's launch, I contacted libretro on twitter and this is what they had to say. I have no I dead what that means other than an implication that improvements from here could be minimal at best. Let me know if this is the wrong place to post this.
Me - "Is there any chance Pcsx - Rearmed for 3DS will run at a playable fps (W/Sound) anytime soon? I'ts been pretty stagnant since it's launch and it seems like its on the brink of running at full speed on New 3DS. Has it been abandoned due to hardware limitations?"
Libretro - "Hi there, our first priority is to stabilize these RetroArch ports first. 1.7.0 (the next version) for instance will have much needed stability fixes, and we'd like to first flesh out and polish some of these console ports first. But yes Pcsx Rearmed was a quick port. There are also no easy quick gains to be had anymore, since 3DS doesn't support NEON so we can't use the NEON optimizations, etc."