I have a sneaking suspicion that the reason a lot of open source emulators (psx4all, etc) run crappy on the Dingoo is because they are not optimized for its CPU. I checked out psx4all, and it seemed to be optimized for ARM (at least as far as any obvious hardware optimizations go). Of course, C/C++ for an emulator like this would be fine for a desktop machine, since optimization isn't as critical due to the adequate CPU power (relative to the PSX's CPU, the same might be said for fast ARM chips). However, for a machine like Dingoo I'd think you'd need to use every optimization you could to get decent performance. Vectorizing some of the code might be a solution as we discussed. I don't know how attractive this is, considering the lifespan of the Dingoo isn't clear. But PSX emulation should be an ongoing project from now until the end of time, if only for archival and research purposes.