how to find and correct plugin query performance issues

There’s an amazing plugin (as usual) called Query Monitor that will give you an amazing set of stats about all the queries run on a page load.

You can see how many queries are made, by which components, how long they take – pretty much everything. I wouldn’t necessarily run this on a live site very much, depending on your traffic & users. Be sure to read the instructions to be sure it doesn’t output to the public.

http://wordpress.org/plugins/query-monitor/