Combined with CPU throttling, it's a decent sanity check to see how well your site will perform on more modest setups.
I naturally assumed that it was my code that was the problem (because I'm often the programmer equivalent of the Seinfeld hipster doofus) and spent the next few hours optimizing the hell out of it. It turned out to be unnecessary but I'm kind of glad it forced me into that "profiling" mindset.
Developers really ought to test such things better.
I had a fairly large supplier that was so proud that they implemented a functionality that deliberately (in their JS) slows down reactions from http responses. So that they can showcase all the UI touches like progress bars and spinning circles. It was an option in system settings you could turn on globally.
My mind was blown, are they not aware of F12 in any major browser? They were not, it seems. After I quietly asked about that, they removed the whole thing equally quietly and never spoke of it again. It's still in release notes, though.
It was like 2 years ago, so browsers could do that for 10-14 years (depending how you count).
I guarantee with 100% satisfaction that my O(n^n) code will allow visitors sufficient time to fully appreciate the artistic glory of all the progress bars and spinners.
Alternatively, run uBlock Origin and NoScript and you probably won't need it.
You can make it look like any feature in any UI is hidden by choosing the longest path to reach it, using many words to describe it despite the target audience already knowing this stuff, and making your windows as small as possible.
Moreover, that a developer tool is a bit hidden in submenus in a UI designed for nontechnical users is fair game.
Even considering this, right click > inspect or Ctrl+shift+k also gets you the web developer tools. Not that hidden.
And then usually the network tab is visible immediately, it is one of the first tabs unless you moved it towards the end (even then, usually all the tabs are visible; but it's nice you can order the tabs as you want, and that a scroll button exists for when your window is too small -- and if the web developer panel is too small because it's docked at the left you can resize it, dock it to bottom or undock it).
This stuff is pretty standard across browsers, it's not like Firefox's UI is specifically weird for this. I don't have ideas for improving this a lot, it looks quite well designed and optimized to me already.
And then no, ublock Origin and No Script can't help you optimize the size of the web page you are working on. You ought to unblock everything to do this. They are a solution for end users, who have very few reasons to use the throttle feature. And unfortunately for end users, blocking scripts actually breaks too much to be a good, general workaround against web pages being too heavy. I know, I browse the web like this.
Any web developer knows how to find the network tab of the web developer tools
Exactly. As you point out, any web developer. My comment was aimed at helping out people who aren't web developers.