efficiency of ODBC, MS-Access, subforms with filter

Hi,

This question might sound a wee bit off-topic but it isn't really.

I've got some tables with related info.
There is a table of customers and some tables with other stuff like
adresses, contacts, letters, ...
Up until now all was stored in a shared MS-Access MDB.

I have a form that shows all the stuff per customer.
The contacts and letters and a few other tables are selected into subforms.
This sucks big time with linked tables out of a MDB via network so I
want to move the backend to PostgreSQL.

Now I try to figure out how I could make my forms as fast as possible.

Subforms can't be based on pass-through-queries in memory so I can
either have linked PostgreSQL tables that get filtered by the form or
create dynamically querydef-objects. Those querydefs would get written
to the mdb-file so I'd lose time again.

Am I to hope that Access tells the odbc-driver the filter crtiterium of
subforms so that it just fetches the few records that relate to the
customer shown on the parent-form?
Or would it rather fetch all records in the source table/view and then
sort the interesting records out locally?