I think I know what the problem is, it's actually a wordpress related bug as I found out.
When using the index table engine, the Author of each post is parsed with a single query by using the get_users() wordpress core funtion. Turns out, there is something wrong with it and freezes for over 10 seconds. Someone else had a very similar issue, but I thought it was only his system affected.
There are 2 things I can suggest for now:
1. Use the regular engine until the next update. I'm working on it right now, and I'm definitely going to find another solution to the user related problem, so it's going to be fixed.
2. Disable displaying the author names on the Layout Options -> Results layout panel and still use the index table enigne.
I'm sorry for this inconvenience, I didn't know about this wordpress related issue before.
Prioritizing the results by user is not implemented yet, it's also coming with the next update. The relevance options panel will be extended a bit, where you will be able to set the priority for the author field as well.Best,
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