Phone is slow after Android 6 update

[asa6680]

Hi sony
I updated new software 6 marshmallow and phone got slowly so slowly try fix with formats ans sony application in PC.. Mobile be fine after this but return again after 2 weeks.. Now I want back to 5.1.1 lollipop 🍭
My questions how to return to previous version "Lollipop? By self in PC..
Thanks

[asa6680]

!!!?

[Emax]

My phone also, laggy. How to repair? Thanks

[Boumediene]

Thanks for everything beautiful Sony Xperia