I'm using the latest google play and beta, both same problem in galaxy S4 and galaxy tab 4 7".
Bluetooth buffer in the way, please remove it. Using iPega 9023 and 9025, games like SMW 2 Yoshi's Island or similar were you need to button smash several buttons and movement Snes9x Ex+ tries to execute EVERY one of them, instead of discarding some that weren't executed on time... weird because framerate is OK, this is a Snes9x Ex+ issue, this doesn't happen with other emulators (ppsspp, epsxe, myboy, drastic). Is not my gamepad, I found a workaround to this.
Workaround is to use a mapper like tincore or gamekeyboard, map the on-screen controls of Snes9X ex+ and the buffer is gone, I can smash the buttons like a mad monkey and the non timed are excluded, this proves snes9x ex+ plus bluetooth = buffer lag.
Seems like this may be happening due to some buffering of bluetooth events by BTstack when a lot of inputs are applied during a large frame skip. I'll do some more investigation and see if I can find a solution.
Any solution yet?