Why speed of search is too slow?

Speed of search is directly related to the store speed and can't be faster than speed of the store product page opening.
To check the speed of search by extension, go to Search > Validate Search Results and click on the tab Validate Speed. Fill in the Search Phrase field with the search phrase and click button Submit.
You wil get the Search Time (seconds) of the search query and Number of Results.

If Search Time is much faster then current search speed on the store, Current Search Engine works correctly. It means that slow speed of search happens due to low speed of the loading store page: a lot of time takes loading of resources. Therefore, you can increase the speed of search only via more precise configuration of the store.

The ways to increase speed of search:

1) If you have a large product catalog (more than 10 000 products), we suggest to use Search Sphinx Engine. See how to Install a Sphinx Engine
2) Set Max number of items in the result
3) Solve all issues which appear at the validator page. Path of the validator page: Configuration > System > Mirasvit Extensions > System > Installed Extensions. Click on the button Run validation tests for all extensions.
4) Try to set the "true" value at the variable $_useNativeTables in the file located at Magento_root/app/code/local/Mirasvit/SearchIndex/Model/Index.php on the line 21.

Factors on which speed of load depends on

1) Store cache configuration
2) Number of products in catalog
3) Conflicts with custom extensions in Magento core
4) Power of your server
5) Usage of shared/managed server on which store is located
6) The traffic flow
7) The server location
8) Type and speed of the connection
etc.