The Widget Cache feature is available in the premium version. You can reduce the number of sql queries with this feature.
Please let me explain the benefit of the Widget Cache with the sample results.
The Analysis result has been generated by P3 (Plugin Performance Profiler) for the Twenty Fifteen theme.
Without Widget Cache
With Widget Cache
Exclude a Widget
You can exclude any widget which you don’t want to be cache.
Update a Widget
If you update a widget, the widget cache folder which is /wp-content/cache/wpfc-widget-cache/ is deleted.
Clear Widget Cache
We did not add this feature not to confuse. You can clear the widget cache with two ways;
1. if you clear cache, the widget cache is cleared as well
2. if you update a widget, the widget cache is cleared
Number of DB Queries
If you wanna see the the number of database queries during the WordPress execution, you should add the following line into the footer.php of theme file.
<?php echo get_num_queries();?>