I got i5 2500

With 3.5 beta i get  up to 208H\s
And it shows pool diff as 50 000 (dwarfpool)

with 3.7 and 3.8 i get max up to 108H\s
And it shows pool diff as 20 000 (dwarfpool)

why is it so?
these are the setting I use:
-o stratum+tcp://xmr-eu.dwarfpool.com:8005
-u 4JUdGzvrMFDWrUUwY3toJATSeNwjn54LkCnKBPRzDuhzi5vSepHfUckJNxRL2gjkNrSqtCoRUrEDAgR wsQvVCjZbRvVs9vWzizq1q1KQyV.Work
-p x
-t 4 (usualy have "-t 3" because there is no difference in hash rate but system starts lagging noticably with all cores loaded)

Also a tryed it on i7 3630Q and i get around same 110H\s with 3.7 and 3.8 miner.