WordPress No Category Base Deactivated & 404s

Hello, I am trying to determine permalink performance related issues with my permalink structure of /%postname%/. I use a plug in called no category base that removes the word ‘category’ in category pages. I am concerned about this change because outputting the match rules yields all 700 categories for every single page. I removed the category base option and yet there are still 700 category matches for every single post, I just don’t understand why it always creates that many of them.

The next thing I can’t figure out is why deactivating no category base causes 404 errors on all of my posts. I hope someone understands what I am asking and can really shed some light onto these issues.

I am hoping to creates thousands and thousands of posts so that google can index them all and so that more users can find the website.

I really appreciate any input anyone can give, thanks.