The noun version of loading can be the abstract as commented above, but because it tends to refer to a process rather than an event, it is also natural and common to use it in referring to things that take some time. "Document loading" implies it is (was/will be) ongoing. That is not due to your slow/fast although the effects of those adjectives in your examples reinforce the effect of the ...
"Being loaded" is the form for present progressive, so it is more correct. The word "as" tells us that the action of loading begins before the man started to speak, and will continue after the man will stop speaking.
Load ing is the process the application performs when it opens a file. Depending on the application and the file, aspects of the loading process could include: Rendering appropriate text in bold, or italics etc for a word processing app with a document file. Performing formulae calculations and rendering charts for a spreasheet program with a csv file. Displaying populated fields in a form ...
For example, a clever user experience designer may trick users into thinking his software is faster by modifying a loading screen, when ultimately the software takes just as long to load.
Netezza, a leader in data warehouse and analytic appliance, has announced its collaboration with Microsoft and the first part of its high-performance data integration strategy for Microsoft Business ...
Search Engine Land: Lazy loading explained: Speed up your site & UX fast