What happens when one saves a form in design mode?

Using Access 2003.

For this application when one enters data and clicks a command button,
code gets run that does the following:

For 5 different combo box controls:
- create a querydef
- querydef is a pass-thru query that calls a stored procedure on a
SQL Server 2000 db
- set rowsource property of combo box to the just-created querydef
- run the requery method of the combo box control

I observed the following:

step 1: enter data and click command button; combo boxes repopulated
after about 4 seconds
step 2: go into design mode of form
step 3: save form (no changes made to form or to the code behind the
form)
step 4: exit Access
step 5: start Access and open app
step 6: enter data (same data st step 1) and click command button;
combo boxes repopulated after about 1/2 second
step 7: exit Access
step 8: start Access and open app
step 9: enter data (same data as step 1) and click command button;
combo boxes repopulated after about 4 seconds

I have replicated these results numerous times, and I have done these
steps at various times throughout the day (trying to rule out the
possibility that slow results were caused because they were run when
lots of system resources in use or network traffic was heavy).
Sometimes, I've run the sequence of steps one step right after
another...other times, I'll introduce a couple hour delay between
steps...same results as far as the time to repopulate combo box
controls.

Questions:
1) If one 'looked under the hood' what would one see Access doing when
one saves a form?
2) Which of the things that Access is doing when one saves the form is
causing the much snappier response time (from 4 seconds down to 1/2
second) the next time the app is run?
3) Is it possible to replicate in code whatever stuff that Access is
doing...the stuff that is causing the snappier response time?

Thank you.