I have obtained a great performance improvement now
just adding an index in the 2 columns 

dtfrom and idcatalogue,

removing the 2 single indexes on the column dtfrom and
idcatalogue.

I could not believe, now the query 

SELECT MAX(DTFROM) AS MAXDT, IDCATALOGUE FROM
CRONOCATALOGUES GROUP BY IDCATALOGUE

takes only 2 seconds in sqlite and 5 seconds in
access.
May be the field idcatalogue has not to be found in
the table anymore because it is in the index (this is
my explanation, but I'm not sure).
Could not imagine such an improvement!

Sorry for my ignorance.


      

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