Since non-XSLT has been removed, looks like part of C4::Search::searchResults() is only for staff interface.
It whould be a better performance to skip it for OPAC.
It concerns items loops @onloan_items_loop, @other_items_loop, @available_items_loop, starting around :
We should try to add a 'unless $is_opac'.
Maybe we could go further and move this to catalogue/search.pl, it would be more clear.
I haven't deep dived this one (yet) but (re)moving unnecessary code sounds good.