block get_content() is called twice on page load.

[danmarsden]

the get_content() function of a block is always called twice on a page load - for that reason we populate $this->content on the first call and then check it at the top and return the content if it isn't null - for an example see:
https://github.com/moodle/moodle/blob/master/blocks/html/block_html.php#L56

Please adjust your get_content function so that it performs a similar check and doesn't run the same set of functions/queries twice on the page load.