It's usually the images in the search results. Each image must be parsed once, and the resizing may take a while if the initial image is large.
What I usually recommend is to limit the search results down to 10 from 30 (on the general settings panel the “Max. results” option)
It should speed up the search by a few seconds.
You can also turn off the images temporary, to see how faster is the search without them. If it's much faster, then definitely the images are the problem.
Let me know how it goes!Best,
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