$ cat imphash.py
import sys
import pefile

pe = pefile.PE(sys.argv[1])
sys.stdout.write(pe.get_imphash())
print ''

$ time python imphash.py ~/PUTTY.EXE
dae4485dd029c5e0256f477eda4797a4

real	0m0.882s
user	0m0.801s
sys	0m0.069s

$ wc -l src/pehash.c
717 src/pehash.c

$ time src/build/pehash ~/PUTTY.EXE
file
    filepath:                        /home/user/PUTTY.EXE
    md5:                             33c9d1e56152e212367e9c5b01671e45
    sha1:                            9ded3ce2ae09c37ca173bbd3dcb57258b72cdbd5
    sha256:                          b10922648f6ad71f3f20b9acdfacf9aeff706cad6c52737cdc426307ccfa51d9
    ssdeep:                          12288:ApoNd4D7aVwSn8nW+nGQZZcLYX4RXwWLJQ6LU:UoNde7aVT8WvQ3O+4NzLu6w
    imphash (Mandiant):              2aad2c1bc86c6d128f6a5152e5b03ba0
    imphash (pefile):                dae4485dd029c5e0256f477eda4797a4

real	0m0.057s
user	0m0.052s
sys	0m0.000s