I've been reviewing my db logs the last few days and found an issue with this plugin. I am using verison 2.0.2 of the plugin.
I saw a lot of queries for "pib_old_version" in the options table in my log. These were happening very very often.
I tracked down the query to the upgrade-plugin.php file.
The main issue I have is that this code is constantly doing the following:
add_option( 'pib_old_version', get_option( 'pib_version' ) );
on line 18.
In addition to doing a DB insert/update, this causes the object cache, which contains all of the mostly static options, to be flushed (I'm using W3TC with Object Caching On).
This has a chain reaction and causes other plugins, etc. to re-populate the cache by doing expensive queries all over again.
In general, the options are relatively stable. They are only updated once in awhile by the admin, etc. By having this plugin constantly updating the options table, it is eroding performance.
Please consider reviewing and changing this code to not constantly update the options table.
I've currently fixed this issue by commenting out the upgrade-plugin.php file. The object cache is no longer being constantly flushed, and the load on my DB server has dropped.