ecpg vs. libpq

I am wondering if there is a fundamental difference in performance
between
using embedded SQL or libpq functions in a C application. If I
understand the
documentation correctly, calls to lecpg are simply transferred to calls
to libpq.
So, the difference in performance is, if any, marginal. Is this right?

Regards, Christoph

PS Sorry if this comes twice, the local mail host seems to be in
trouble.