Does your site load slowly all the time?
Is it when you have heavy load?
Does you site load slowly from the server itself?
Do other app pools have the same problem? Setup another site with a seperate app pool to test this if you have no other sites/pools on your site.
Maybe you need to do some architectural design and split your existing site into multiple apps and app pools.
I am not sure any app pool settings from the defaults can really help much in many cases.
You could increase the kernal request queue but the default should be enough for most cases. You can always try and increase this to see if it solves your problem.