If possible, try making a local copy of these external tables, and link to
the local tables, just for testing purposes.  If the speed improves, then you
know it is the external tables causing the lag.  If the speed doesn't
improve, then it is a local condition.

Go to Tools, Options, General Tab and turn off Name Autocorrect on all of
your databases. IMHO it's a piece of do-do and the cause of many problems.
While there turn off Compact on Close if enabled. You'll be glad that you did.

Also temporarily turn off your virus checker for a quick test. If that makes
a positive difference there should be a way to exclude .md* files from
testing in the virus checker.

Also you might want to compare the criteria in the queries to the indexes in
the tables. If the Where clauses says something like EndDate > Now() and
there are more than a thousand records, putting an index on EndDate may speed
things up dramatically.