RedHat 7.0 sed speed is slow

[Woo, David]

I'm transferring a shell application from SCO 5.0.5 to RedHat 7.0.  Of all
the things that I thought I 
would have no problems with, I never thought that the speed of the sed
command on SCO would 
run 4 times faster than the one on RedHat!  The original sed on SCO had been
running slowly - so I 
had compiled the GNU version of sed on SCO - and had reduced the execution
time from 3 hours 
to 40 minutes.

Now I have transferred the exact same script that calls sed extensively from
SCO to the standard, 
stock RedHat 7.0 distribution - I find that the RedHat sed is running 4
times slower than than the 
SCO GNU version of sed - just like the original SCO sed.  Isn't the version
that comes with RedHat 
the GNU version already?  The RPM reveals that RedHat sed is "sed 3.02-8".

I'm such a newbie that I don't even know how to update to the latest version
of sed - and don't 
know if it would help?

What am I missing?

TIA.
David.