Default Ainol Novo 7 Venus - Best Rom ?

Hi! I know this device maybe outdated but would still like to know what is the latest and best Rom for Ainol Novo 7 Venus? I remembered that I updated the firmware to 4.2.2 and after a while, the device is now super lag. I thinking of installing a new rom which is faster and more stabler. Please Advice. Thank! Also, please point me to where I could get the software and tutorial to install it. Cheers!