Can you elaborate more on crazy amounts? That should definitely not happen, as repetitive page loads are cached to prevent further query executions. First page loads are of course heavier, as the plugin looks for related posts within the database based on keywords parsed from the configured fields. For more info you can read about a performance test I concluded on related posts plugin: https://wp-dreams.com/articles/2014/11/related-posts-plugins-performace-measured/
I can see an error in that query. There are unexpected “&” and “*” characters, which makes it failing. They look like they are part of html entities, and it's very hard to escape them.
Since I can't see FTP access I've quickly made a change in my local test environment to the word parser function, to look for more unexpected cases. So far I'm getting positive results on all stress tests.
I'm attaching this version to this post, please re-install it to your server, save the settings again, and check if these errors appear again.
If the problem still persists, and you can provide temporary FTP acess as well, I will gladly debug through the code to find the source of the issue. I'm hoping that the attached version will help though.Best,
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