I have patched the "bitcoinr" to use system provided crypto, here is the result:
CPU: Premium III Mobile (yes, i know this is very very old)
Compiled with gcc 4.4, -O3 -msse
the cryptopp 5.6.0 in bitcoinr tree: 133khash/s
the cryptopp 5.6.1 (provided in debian): 200khash/s
Out of curiosity, what speed do you get from various algorithms in the
CPU miner? That also uses Crypto++ code.