Are you sure the bottleneck is in Perl? Have you benchmarked or dproffed that? The way I understand it, PerlMagick is but a very thin layer on top of a very optimized ImageMagick. You may be spending most of the CPU's time in optimized C code already, which makes it rather pointless to start doing the remaining Perl bits in C.

This probably doesn't help you directly, but may put you in a better position when discussing this with your client.

Liz