Very slow processing...

Hello all,
I have successfully installed and debugged the installation and
uninstallation procedure.It works fine.But when I try to debug the
functionality like IRP_MJ_CREATE and IRP_MJ_CLOSE, it is very very slow.It
tyales at least 15 seconds to complete one step over or step into and til
that time the procedure usage is 100%. It is not the case that I am having
a slow machine. I have P IV 256 MB Ram 1.6 GHz. still it is very slow.It
is comparatively fast while I debugged the installation and
uninstallation.
What might be the cause? I am using WinDbg 6.0.
One more thing is that if I place a breakpoint after 5-6 statements the
the current instruction then it takes same time to complete one step over
or step into.Strange.
Anand.