Kaspars

Use PHP output buffering to extract widget output and store it into WordPress transients for faster retrieval. It also adds a checkbox to widget controls to exclude it from being cached.
It is a quick fix for bad behaving plugins that parse RSS feeds or call remote URLs on every page load.

Widget Output Cache

Improve website performance by caching widget output in WordPress transients.

Philip Newcomer

Sometimes developers need to filter the output of a widget that does not have its own output filter built-in. This plugin provides a filter which will allow developers to filter any widget’s output, regardless of whether it has that capability natively or not.
This plugin was inspired by a similar filter in the <a href="https://wordpress.org/plugins/widget-logic/" rel="ugc">Widget Logic</a> plugin, and essentially duplicates that functionality, but with more flexibility.
Usage instructions are <a href="https://github.com/philipnewcomer/widget-output-filters" rel="nofollow ugc">on GitHub</a>.
This plugin is developed <a href="https://github.com/philipnewcomer/widget-output-filters" rel="nofollow ugc">on GitHub</a>, and is available as a <a href="https://packagist.org/packages/philipnewcomer/wp-widget-output-filters" rel="nofollow ugc">Composer package</a>.

Widget Output Filters

A library which enables developers to filter the output of any WordPress widget.

Widget Output Cache vs Widget Output Filters