You can turn off the search in posts, search in pages options on the backend, on the general options tab. But if you dont need those options it's faster to add the following lines after the code I provided earlier:
This will make the search ignore everything after printing the category results – will make it somewhat faster.
You probably want to get rid of the settings box as well, it's not needed for this kind of search. The best was to do this is by turning off everything on the “FRONTEND SEARCH SETTINGS” panel and after saving the options, the settings box will disappear from the frontend.
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