I *really* need some help on a problem baffling me. Something has changed but, honestly, neither my manager nor myself can figure out what!

Background (in a nutshell):
We have a multi-user VFP application that has run well for years.
It's currently running under VFP8.

One part of this application sometimes does a "Select - SQL" lookup on another department's .DBC. This lookup has taken approximately 1 second.

I recently added six small non-indexed fields to the lookup table in the "other" department's application.

The problem:
The next day users in the "first" application found that the lookup time increased from 1 to (now) 18 - 20 seconds. Please note that the "first" application's code is absolutely UNchanged!

When I do the same lookup in a non-production "development" .DBC, I still get the quick (1 second) results. Otherwise, I too get the big delay. (Both tables' record counts are quite similar and the new fields are also in the development table.)

Both .DBCs, production and development, are on network servers (not local). The issue is reproducible and results depends upon which "other" .DBC, production or development, I do the lookup on.

Here are some basic facts, related or not:

1) During this period our network has not changed.
(My manager is the network administrator.)

2) All users now encounter the same issue.

3) The problem is server independent. That is, the "production" data when
copied to the "development" server exhibits the identical 20 second delay.

4) When the fields were added to the "other" department's production table,
I used VFP9, not VFP8.

5) At that time I also reindexed the table's three tags using the
REINDEX command and packed the table's memo fields.

6) I have carefully checked and rechecked the tags' key expressions.
I have also deleted TAGS ALL and recreated each tag from scratch.


Summary:
None of my efforts have shed light on the problem or have restored the quicker lookup to the production data.

It is like the "other" production table or .DBC has been somehow contaminated.
This is now a production issue.

I really need some fresh thoughts and insight. Any help is most appreciated!