Your Pentium 4 processor might be your problem.  FSX places a
huge demand on the processor, and with  the C-130X on top of
that, things will slow down a great deal.

Try backing off on all your sliders and see if that helps.

Also, try dropping the Ac Pack and run only SP1 and SP2.
Ac Pack causes slow downs on some computers.  It did
on mine.

With SP2 you don't need all  those tweaks.  Some will slow down
your system.  Check out Phil Taylors blog on http://blogs.msdn.com/ptaylor/default.aspx

Defrag your system on a regular basis and get rid of any programs
you don't use.  Run your computer as clean as possible.

I hope this helps.