And the constructor is called very often - once for each contact being {de}serialized
by Akonadi (see VCardConverter::parseVCards).

Fixed by the usual "static const struct" readonly-data solution (from Marc Mutz in libkleo).

I hit this when using the "Select..." pushbutton in kmail composer, which fills in a model
with all contacts.

Validated by the unittests (which are the reason why I had to sort both lists
alphabetically, to match the ordering that was done by QMap previously).