Hi Raj,
If you are not on SP05, then which version are you currently on. Can I suggest you to request your basis / admin to plan for the upgrade. There had been quite positive changes with respect to the performance in the recent revisions. If you compare with revisions earlier to SP05, then there has been significant improvement in the performance. We have observed noticeable performance gain after upgrading from revision 61 to revision 66.
Rather than trying to fix any issue for the performance, I'd suggest you to upgrade to the recent revisions and then check the slow performance issue.
Regards,
Ravi