Many modules have become quite large over the years and should be split into more purposeful modules.
An example of the benefit of this is stream.php which includes many other modules to gain just a few functions. Hidden in those other modules are events that we don't need in stream.php. ie. page.php will reload the style if caching is disabled, settings.php will check for and download messages. These events are hindering the performance of stream.php, and many other modules.