I actually audibly laughed when Raspberry Pi came out with an 8GB version because for anyone who thinks 4GB isn't enough probably won't be happy with 8 either.
I wonder what the hell they are doing with it? I mean I have the 3B with IIRC 1GB and I can use the desktop and run python scripts to fiddle with all the I/O ports and stuff, what do you do with a raspberry that needs eight times the RAM??
Last time I asked around about this question, the answer was surprisingly "probably not much"! When a low-power x86 chip (like those mobile chips) is idling (which is pretty much all the time if all you are doing is hosting a server on it) it consumes very little power, about the same level as an idling Pi. It is when the frequency ramps up that performance-per-watt gets noticeably worse on x86.
Edit: My personal test showed that my x86 laptop fared slightly worse than my Pi 3 in idling power (~2 watts higher it seems), but that laptop is oooooooold.
My main machine at home - a M2 Pro MacBook with 32GB RAM - effortlessly runs whatever I throw at it. It completes heavy tasks in reasonable time such as Xcode builds and running local LLMs.
Work issued machine - an Intel MacBook Pro with 16GB RAM - struggles with Firefox and Slack. However, development takes place on a remote server via terminal, so I do not notice anything beyond the input latency.
A secondary machine at home - an HP 15 laptop from 2013 with an A8 APU and 8GB RAM (4GB OOTB) - feels sluggish at times with Linux Mint, but suffices for the occasional task of checking emails and web browsing by family.
A journaling and writing machine - a ThinkPad T43 from 2005 maxed out with 2GB RAM and Pentium M - runs Emacs snappily on FreeBSD.
There are a few older machines with acceptable usability that don't get taken out much, except for the infrequent bout of vintage gaming