The email app has greatly improved in speed. opening attached pdfs was a real pain before and now works nicely. I know because i open about 5 pdf order attachments per day and since yesterday it feels like someone pulled a stick from the gears.

xperia x specific i can not see much improvement.
At first i thought wake-up-freeze was fixed but i got it in usual frequency if the phone wakes from sleep...
I am sad that bluetooth issues still persit. I actually listen to music much fewer since i use xperia x and my JBLs are collecting dust