Because 4.3 is worst firmware I ever tested,to bugy and lagy.
Its like 4.0 for xperia ray,now I feel that xperia ray is faster than this peace of sh..t!
Here is it little tutorial for downgrading if somebody needed:
1.Backup everything that is important (music,pictures,..)from internal storage to sd card or pc
2.Backup contacts on sd card
3.download stock TFT file from this thread http://forum.xda-developers.com/show....php?t=2311964 for all version of Sp
for Sp 5303 I'm using this TFT file https://docs.google.com/file/d/0B7GI...dDA/edit?pli=1
4.flashtool tutorial thanks to mrjraider http://forum.xda-developers.com/show....php?t=2658952