What is ajax search? Ajax search is a kind of search autocomplete that displays search results for every keystroke. The search results are updated dynamically on a webpage without reloading the entire page. Ajax search stands for Asynchronous JavaScript and XML search.
I currently have 1 million custom posts.
What you don’t understand, is that Search functionality ESPECIALLY AT YOUR SCALE , will consume so many resources that it is not feasible to keep them part of your hosting plan. YOU NEED TO OFFLOAD the search functionality to something like Elastic Search using Elastic Press.
Plugin is only as fast as the underlying architecture, maybe look at why it’s slow instead of clogging it up.
In general yes in this case yes the WordPress architecture is the issue.
It doesn’t scale at all for large databases doing joins and %LIKE%