You should try it with tcatm’s 4-way SSE2 SHA in sha256.cpp.
Added. Users may select this by enabling SSE2 instructions in their compiler during build, and then
$ minerd --algo=4waywill select the 4way implementation, rather than the default ‘c’ implementation. Run “minerd —help” to make sure 4way is listed as an available option first; if not, you did not build with SSE2 enabled (-msse2, or many values of -march=xxx).