PPSSPP poor performance on Galaxy S4

[fivefeet8]

Unfortunately, your experience is not distinct only to you. I've had that same device in the past and had the same performance. You'll need to enable auto framekip up to 3 in most games and use only at most 2x Resolution. Probably going to be mostly staying at 1x Resolution.

The Snapdragon 600 is simply too limited for PPSSPP in terms of hardware and drivers. Especially drivers. They're not what I would call great.