If this sounds like homage to my earlier post with a similar name, you're right. There's just as much to be learned from running a low end client as there is from running a low end server.
The other day I was working on a blog post from my notebook, and after it published I spotted a change I wanted to make in the homepage template. I'd already determined that the template editor was working reasonably well in production, so I fired it up and set to work.
Within seconds, the CPU on the notebook ramped up to 40% and its fan started blowing enough hot air on my thigh to singe my leg hairs.
mutationObserver event was running wild, apparently triggering itself in an infinite loop. I suspected this was code originally used to handle event changes in the post editor, but which wasn't being modified to handle the behaviors of CodeMirror for the template editor, so I threw in a quick hot-patch to deal with it. Turns out I didn't need that particular piece of code for CodeMirror anyway, so I made a note to make a more permanent fix later.
Here's the thing: I would never have known about this issue on my super-duper-over-mega-hyper-powered desktop, which I can't tell if it's breaking a sweat even when all eight cores go into 100% utilization. I only found out about this because my notebook was comparatively underpowered (although it's still pretty good: four cores, 8 GB RAM).
If I hadn't bothered to try and use something other than my desktop, I might well only have found out about this when some poor sap with a far less powerful notebook or PC than mine tried to do the same thing. I'm glad I spared him at least that much pain.