Hardware and performance

I do not know much about your situation, so I can only give very vague recommendations. I think this breaks down into two areas:

1. Generic web hosting concerns
2. Moodle-specific

For example: should you host many GBs of HD video directly using Moodle, or advise users to use a dedicated video platform (Vimeo or YouTube)? That's a general question for any web application, but there are specific ways you can address or prevent it in Moodle.

You might also want to look into:

• Course size plugin. Not a perfect measurement, but it can help you identify outlier courses.
  
• Are you saving a lot of automated course backups?
• What are the file size upload limits for your site, courses, and individual activities? https://docs.moodle.org/37/en/File_upload_size
  
• Are any of your database tables particularly large? Are you using any custom plugins that are misbehaving? I had a plugin that was writing millions of lines of event records to mdl_logstore_standard_log, and it turned out to be a pretty quick and reasonable fix once I showed it to my developer.