A sure way to slow down ADO!

This is unbelievable!

My application (Delphi 5 + ADO for accessing Access 2000 mdb) was working
well, very fast (despite ADO :-))). Then, after playing a little with
charts, I have noticed incredible slow down in my application in non related
part of program which code I have not touched at all. But this code was
using same table as chart did for other kind of analysis. Processing become
very slow, at least 100 times slower than few minutes ago. Apparently
without any reason. I have repaired, compacted mdb, ... with no result. I
have also deleted all charts. No result.

And guess what I found to be problem? Because of chart, I have added two
look up fields (lookup fields all indexed) in fields editor of TADODataSet.
Before that, in fields editor I had only structure of table (no lookup or
calculated fields).

***IMMEDIATELY after removing this two lookup fields and recompiling, my
application execution speed of data analysis was instantly back to normal!!!
No other change!!!***

But what is also interesting: ***RECREATING*** same two lookup fields has
NOT again slowed down my application! I've found also being effective making
a copy of TADODataSet, then deleting fields from original dataset, then copy
& paste back to original TADODataSet!

I guess something went "wrong" because of fields editor or some file get

After so many debates on ADO processing of data being slow I have been
following for about one month to help myself, I hope this "discovery" will
help at least some of tormented ADO souls! :-)) I'm wondering if this helped
somebody else, too.

Unfortunately, this is not cure for all problems with ADO. I have another
very small application (with no fields loaded in fields editor in any
table), which sequentially edits & updates (only scanning and searching is
not problem, edit & update is) about 37.000 records with data from another
lookup table. It is at least 100 times slower when data resides in Access
2000 mdb file than when I work directly with BDE and dBase DBF format. No
other change. :-(