Strange, for x86_64 aes-128 (and others) are much slower for small sizes with asm than without. with asm: aes-128 cbc 99800.49k 106699.15k 108852.40k 277620.74k 281411.58k w/o asm: aes-128 cbc 146135.83k 155790.60k 158851.09k 159470.71k 159413.51k Regards, Michael