I've had the OP2 for about 6 months now and I've had tons of problems with the Oxygen OS. The main problem I had was it would get very very hot, up to 60 degrees Celsius, and it would get so so slow. So then I flashed CM12, but as everyone knows it doesnt have fingerprint sensor, and the camera usage by third part apps like snapchat will crash the phone. So I'm planning to go back to Oxygen OS and see maybe completely erasing and flashing may work.