Pete,

Not sure this is exactly what you are looking for, but I'll give it a shot.

If you have a report that is based on a query that takes an inordinate
amount of time to run, and are not concerned with how current the data in the
report is (once a day refresh is fine), then what I have done in the past is
create a new table which has the structure needed for your report.

Then, I add a field (rpt_xxx_Updated_at, DateTime) to my db_Parameters table
(have one of these for almost every database).  Then, when someone wants to
run this report, I check to see whether the value in this field is equal to
todays date.  If it is not, then I run a couple of lines of code that delete
the old data and insert the new data into this table and update the field
with todays date.  It might look something like:

Private Sub cmd_Report_Click

   Dim dtLastUpdated as date

   dtLastUpdated = NZ(DLOOKUP("rpt_xxx_updated_at", "db_Parameters"), 0)
   if dtLastUpdate <> Date() Then
       currentdb.execute "DELETE * FROM tbl_rpt_xxx"
       currentdb.execute "qry_rpt_xxx_Insert"
       currentdb.execute "Update db_Parameters " _
                               & "SET rpt_xxx_updated_at = #" & date() & "#"
   endif
   docmd.openreport "rpt_xxx"

End Sub

This way, only the first person who runs the report actually generates the
data for the report.  If you need the report to be more specific, then use
the WHERE clause of the OpenReport method to restrict the reports result set.

You update data in a table with an update query.  This will cause row level
locking (or page level locking if your db is in that mode) for each row that
you're updating while updating it, but it won't require a table lock.

   dim db as database
   set db = currentdb
   db.execute "update ReportData ...", dbfailonerror

If all the data needs to be replaced, delete the rows in the table first and
append the rows located in the table you wanted to overwrite the report's
table with.

   dim db as database
   set db = currentdb
   db.execute "delete * from ReportData", dbfailonerror
   db.execute "update ReportData ...", dbfailonerror

If you overwrite a table, you need a table lock to keep others out while your
operation completes.  It doesn't really matter if you overwrite the table
with the same structure or not.  It's the table lock itself that's important
when dealing with contention issues.  You can't get your needed table lock if
someone else already has a row level lock because a row is being updated.

Chris
Microsoft MVP