Notes/Domino 6 and 7 Forum : HTTP Performance tuning

I'm looking for assistance to do some parameter tuning on the http settings in the server document.

assuming the settings are default on the "Internet Settings" "Domino Web Engine" page of the server document, which of the settings, if any will yield the best improvement to the server.

the issues are that cpu utilization and disk i/o are increasing. The stats for the server are:

Domino.Cache.Command.Count = 17
Domino.Cache.Command.DisplaceRate = 0
Domino.Cache.Command.HitRate = 1.05452759128869
Domino.Cache.Command.MaxSize = 128
Domino.Cache.Database.HitRate = 32.8861582398587
Domino.Cache.Design.Count = 128
Domino.Cache.Design.DisplaceRate = 10.9185649176543
Domino.Cache.Design.HitRate = 89.0225674563207
Domino.Cache.Design.MaxSize = 128
Domino.Cache.FormsCache.Count = 0
Domino.Cache.FormsCache.MaxSize = 256
Domino.Cache.HaikuDesign.Count = 0
Domino.Cache.HaikuDesign.MaxSize = 256
Domino.Cache.iNote WA Forms file.Count = 0
Domino.Cache.Note Cache.HitRate = 0
Domino.Cache.Session.Count = 40
Domino.Cache.Session.DisplaceRate = 0
Domino.Cache.Session.HitRate = 0
Domino.Cache.Session.MaxSize = 1,000
Domino.Cache.SkinGroupsCache.Count = 0
Domino.Cache.SkinGroupsCache.MaxSize = 256
Domino.Cache.User.Count = 38
Domino.Cache.User.DisplaceRate = 68.1339763563353
Domino.Cache.User.HitRate = 25.8889528383644
Domino.Cache.User.MaxSize = 128

It appears to me that the user displace rate is too high....what kind of memory penalties might I incur by increasing the max cache size?