Slow MDB Linked View

I previously posted re. this, but thought I'd try again with a summary of
facts.

I have an Access 2000 MDB with a SQL Server 7 back end. There is a view that
is linked to the database via ODBC and has been in place for several years
without any performance problems.

Recently I added a couple of fields to the output of the view, and it became
very slow when scrolling. When just opened in the database window, the
linked view takes about a second to scroll down one screen. When opened in
the form (in Continuous Form view), it takes about 2-3 seconds. It used to
scroll just about instantaneously.

I tried removing the few fields I added to restore the view to its previous
form, but it had no effect. The view was still much slower than it had been.

The total number of records returned from the view is about 1300, so it's
not a large number of records. The view has about 25 fields.

I found that when I link the view in the MDB without specifying a unique
index, it scrolls very quickly -- almost instantaneously. But when I specify
the unique index, it is slow. Since the view needs to be edited, it needs
the unique index defined.

As noted, it's been in place for years, with a unique index defined, yet
without the slowness. Any ideas as to what might have caused this and what
might be done would be appreciated. I've included the SQL for the view
below.

Thanks,

Neil

SQL FOR MAIN VIEW:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL FOR vwInventory_Dupes:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))