The download speeds from google playstore have become extremely slow since the last couple of days. Everything else seems to be downloading at the normal speeds, please help!

I've had this Z1 for about 11 months. I can only get around 2h on screen time with regular usage. The battery uAh is only 1848000 which to my knowledge is around 1800mAh. I've tried calibrating the battery before and I am trying it again.
The phone is rooted on stock 4.4.2. The lollipop software keys are from a theme.
I have tried updating to Lollipop before but received an error due to rooting, so no observable changes have happened.
If there are any threads with solutions please point me to them as I have not found any with a uAh as low as mine.
Any help would be appreciated.

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