Share your experience!
Hello Guys,
I bought z3 few days ago it got brand soft from Orange, but i have an issue with lockscreen i changed wallpaper from Xperia one and sometimes when i push power button it's shows blackscreen and 1 sec later my lockscreen wallpaper appears. How to fix it? I have read that even non branded soft got this problem. 
Your firmware is changed by Orange. So the xperia wallpaper lags ?
Yes original wallpaper from xperia lags
See if in safe mode the same occurs:
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008
Yep this same lag ;/
You could try to perform a software repair but not sure if it will work. Contact sony:
http://www.sonymobile.com/global-en/support/contact-us/