If you make more than 7 unique requests (excluding homepages) within a 5 second window to the front-end (opening 7 or more links super fast).  That triggers throttling because it's a common tactic of bots to just start crawling different URLs of the site, and different URLs would have an inactive page cache, causing full renders, causing higher load on the server.
Once you are flagged by portas as having bot-like behavior, your requests are throttled for the following 2 minutes.