If they use old kernel, drivers and so on then where these lags and bugs came from? Because AOSP Lollipop for MI2 is so smooth and ready for daily use. Maybe they are still trying to integrate new drivers?
http://www.ipetitions.com/petition/give-xiaomi-mi2-official-cyaogenmod-support - here's the petition for official cyanogenmod support for our device. there's just 400 signatures left. it's our chance)