samsung galaxy 3 clone/china

hello

i have sadly purchased a clone samsung galaxy s3/china

model number GT-I9300
andriod version 4.0.4
baseband version maui.11amd.w11.50.sp.v20,2012/08/13 14:56
kernel version 3.0.13 1211 v 16 fri aug 31 18:38:05 cst 2012
build number IMM76D.I9300ZSALE9
coustom build version 1346409495

and it is very very very slow and just not responsive at times is there any way that can be fixed? and it there a way i can use the phone. because in the current condition it is too slow to do anything with it.
if there is a root or anything plz let me kn (i need all the help i can get)

-thank you