You might want to add tags to that list, depending on how and if you use them.
Many months ago I was at least one of the original 'complainers' that triggered chaley to add this feature which is a must have setting for me too. My rationale was not for performance reasons, it was to do with the quality of the search results. You no longer have to prefix every search term with the likes of title: etc just to quickly find the book you are after as you no longer get all the false positives from random word matches in comments etc. That this feature also improves performance is just an added bonus to me!
Note that you can still search other fields with your list restricted, you just need to prefix them like comments:xxx