There are two types of attributes you can add to a
<script> element that will specify how the file will be executed (these attributes specify how the HTML parsing will handle the script files).
The two attributes are asynchronous and deferred.
In most cases, when these attributes are not specified, HTML parsing pauses for the script to be fetched and executed, thereby extending the amount of time it takes to get to the first paint.
Mouseflow uses the deferred attribute.
The deferred attribute tells the browser to only execute the script file once the HTML document has been fully parsed.
Like an asynchronously loaded script, the file can be downloaded while the HTML document is still parsing. However, even if the file is fully downloaded long before the document is finished parsing, the script is not executed until the parsing is completed.