Because of India customers complaining about heat issue, in V45 firmware the CPU was downclock to 1.0-1.2GHz (so cooler now), and some of them said its running dual core only. You can use cpu-z from playstore to check the cpu speed. That's why now they complain its laggy, especially when playing games.
Unfortunately xiaomi sometimes will re-direct the forum response to another page and now its quite hard to find some of the indian customers complaint/reply. Like I wrote something in Hugo's V45 thread and somehow it was moved to another thread, making his thread 'clean'.
Redmi 1S update Version: JHCMIBH45.0