I can't tell which version of Moodle you're using, so... If you're using Moodle 1.7 and loading the moodle/index.php page is slow, then in addition to any Apache tuning which you may have to do, it could also be as a result of a query which works out the roles, capabilities and overrides of the user. Take a look through the posts in this forum especially (http://moodle.org/mod/forum/discuss.php?d=58208) and also MDL-8120.
Hope this helps!
I would just like to add one thing to Ken's excellent reply: if you have a way of monitoring queries going through your database, this could tell you if it's a slow SQL query. I was able to start MySQL with the --log-slow-queries parameter and monitor this log for indications that our database was a bottleneck. If you have a number of users, courses, or content, you might be affected by the MDL-8120 issue. A forum thread discussing this can be found at: http://moodle.org/mod/forum/discuss.php?d=61845
However, if you log the slow queries it might steer you in the right direction.
As I look at it more, I think it might be a php issue. So I wanted to look and see if I could use a php accelerator. I went to the Moodle/php folder and I see there is a folder marked for eaccelerator and zendoptimizer. I want to use eaccelerator and I see that there are only 4 files in there - eaccelerator.php, eaccelerator_password.php, encoder.php and a readme. I then went to the eaccelerator site and downloaded the latest release. How do I now use it? Do I just extract the files to that folder and open the eaccelerator.php file? I tried looking at http://eaccelerator.net/wiki/InstallFromSource and there is just so much I am unfamilar with there to make sense of it.
Did you check the obvious? $CFG->wwwroot = 'http://the.way.you/moodle'; in your config.php?
Is this the way you debug Windows servers? You speculate "something wrong with PHP", and then? reinstall PHP? Add RAM, add an accelerator? All that sound very tedius to me
If your customer is a proffessional institution, consider switchting to a Unix flavour.
If I had control of the budget, I would consider switching OS's, but since the Windows server is in place, that is what I have to work with.
-how is your Windows DNS resolution set up?
-is Apache configured to do a reverse DNS on the client?