Off-topic: what is the site doing "checking your browser" for five seconds before showing the content? I know that this sort of data can be valuable - what bro

Off-topic: what is the site doing "checking your browser" for five seconds before showing the content? I know that this sort of data can be valuable - what browser I use, which plugins are there - but I just assumed everyone was doing this in negligible time frames. What more is there to check in a browser?