1. You can turn it off on the layout panel: https://i.imgur.com/X6tiiWA.png
2. The speed mostly depends on:
- The amount and quality of the wordpress plugins installed.
- The server response time
- The database size
80% of the time of the ajax request is the loading of the wordpress core. Some plugins load themselves on ajax requests as well – that's a huge slowdown. The only thing to do about this is to try other plugins or try the search without plugins.
Big databases also can affect the speed, but usually under 10 000 records they are barely visible – I think it's not your case.
The server response time can be very different from different locations and the wordpress core affects it exponentially.Best,
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