Hi, I have a Lenovo A6000 single sim with his stock rom s025 kitkat and is very laggy.... What can I do to solve the lag? I have this phone by 1 year, first runs very good, after I upgraded it to stock lollipop, which was very laggy, I flashed back the stock rom kitkat for dual sim, after that I flashed some custom roms (MIUI 7, CM 11, VIBE UI 2.0), very laggy, after that I flashed the stock rom kitkat for single sim and is very slow. * I 'm not playing games on the phone, I have all the apps updated *