PHPMapscript/Linux horrible performance after Apache 1.3->2.0 upgrade

[Hal Mueller]

My hosting company just surprised me with an "upgrade" from Apache 1.3
to Apache 2.0, as part of a solution to some other problems.  After
reinstalling Mapserver, I am seeing performance that is less than a
tenth of what I had before.  Server is running Redhat Enterprise
Edition behind an Ensim virtual hosting package.

I've gone through installation carefully, and I think I have
everything right.  But when I reinstalled Mapserver I updated several
supporting libraries.  I want to make sure I'm barking up the right
tree.  I suspect Apache is the problem.  Am running PHP as a separate
CGI.

What I am seeing when I run "top" is that the PHPCGI processes take
over the machine.  This didn't happen before.  I had a steady system
load of about 0.7 and was able to service all requests; now I see a
server load of 10-20 (!) and am serving only about 10%.

Any suggestions on things to try?  Is this slowdown between 1.3 and
2.0 a known (or familiar) problem?  Haven't tried FastCGI yet.  I
really want to understand what has happened, and why, before I inject
more changes into the environment.

                 Old:                   New:
Apache      1.3                     2.0.50
Mapserver  4.4.0                  4.6.1
PHP          4.3.8                   4.4.0

Am now using PHP-bundled GD.

mapserv -v
MapServer version 4.6.1 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP
OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=FREETYPE INPUT=EPPL7 INPUT=OGR
INPUT=GDAL INPUT=SHAPEFILE


TIA,
Hal