Pi 1 Model B slow, choppy audio video. bad PSU?

[scar]

I have one of the first Pi's, model B... I read this version will run fine the older emulators like NES, but mine isn't. I installed Retropie 4.1 and it installed and runs fine, loads up Emulation Station and recognizes my Xbox360 controller.

However, it can barely run even a simple NES game like Super mario bros. 1. The video is slow and the audio is slow/choppy. I tried using both of the NES emulators, tried changing the video mode for the emulators to a low res (CEA-1 and DMT-4). retroarch uses about 93% cpu when the game is launched.

I tried overclocking using raspi-config Modest and Medium settings. On the medium setting, the USB receiver starts powering off and on and i can't use the Xbox controller, so that is why I was thinking it was the PSU. The details are below, it's the PSU i got with the Pi when I bought it from Newark/element14.

Either that or the Xbox Controller receiver draws too much power? The docs it came with say it uses 5V/500mA. I notice the game runs slightly better when i just have a USB keyboard plugged in. So i have to buy better power supply or simpler controller? or are there some other steps i could take first to see if performance could be improved?
Thanks

Pi Model: B (HW rev. 0003)
Power Supply: MCM/MW I.T.E., model MWS5-0501000UC/MICRO, 5V/1000mA
RetroPie Version: 4.1 (0/1 version)
Built From: Pre made SD Image on RetroPie website
USB Devices connected: Official MS XBOX360 USB receiver (Model 1086, P/N X809782-009, PID: 84294-623-9234111-31633)
Controller used: Xbox 360 controller
Error messages received: N/A
Log found in /dev/shm/runcommand.log: http://pastebin.com/hcE0N7ek
Emulator: lr-fceumm, lr-nestopia

[AlexMurphy]

@scar Switch to the lr-quicknes emulator. Works better with Pi 1/ zero. Get a better PSU ~ 5V 2A output.

[scar]

@AlexMurphy Thanks! lr-quicknes is working good. Also found pisnes works better for the SNES