ECO fast recompilation

Right now I am using quartusII 9.0

I have a design fullcompilation that take up to 7 hours.

If i have reserve the top level design partition at post PAR level with reservation at level of placement, routing and high speed tiles.

if i try to make 2 io pins assignment swap. How can I have fast recompilation time? Do I still need 7 hours compilation times?

please reply me asap.