List View Threshold optimization

We had a problem with some large list performance, and increased List View Threshold to 120000 and List View Lookup Threshold to 16 in trying to rectify short-term.

Since then, we've reorganized the lists, added indexes and columns, etc. I want to reduce the threshold values as close to Microsoft SP (and SQL table locking) recommendations as we're comfortable with. We have not noticed a significant change in page load times of the site overall, or heard complaints from users regarding performance caused by rendering a large list bogging down the rest of the site. The temptation is to put them back to 5000 and 8, but I'm not trying to generate user frustration.

Is a tool that would capture our site's performance and present a recommendation? Or certain red flags I can monitor that would suggest we need to increase as we throttle back?

Thanks!

Scott