I've recently bought a Lenovo ThinkPad T480, i5-8350U, 16GB, 256GB SSD, which does everything I need from a laptop (I mainly use my desktop PC anyway).
My old laptop is a Travelmate 5720, Core 2 Duo T7300, 4GB, 128GB SSD. It boots fairly quickly and it's usable for basic stuff like browsing, but running Windows 10 the CPU is at 99% most of the time just from the background Windows processes, so the noisy fan is running at full speed, and doing Windiws updates takes ages
It's not worth spending any money to upgrade the RAM or SSD, but I could replace the DVD drive with a spare 256GB that I've got. The current SSD is almost full but that's because I've got dual-boot Windows and Linux installed, so if I was only running Linux it would probably be sufficient.
Before I scrap it (I'll keep the SSD), I was just wondering if there's anything that it might be better suited for than my desktop, laptop, M700 SFF PC (which is my main self-hosted machine and backup server) and my various RPis?
Maybe being portable gives it an advantage for some task over the other machines? The battery isn't great, probably runs for an hour or so, but at least I can disconnect it from the power and move it around without shutting it down, and it will keep running for a while if there's a powercut, or I have to turn off the mains to do some DIY. Of course, my modem/router wouldn't have any power then, not would any of my other PCs, but I could use my phone as a temporary hotspot to maintain connectivity for whatever is running on the laptop.
Or maybe having a keyboard and monitor gives it some advantages over the RPi for some particular task I haven't thought of? The M700 won't have a keyboard or monitor connected most of the time either, but I'm not sure it matters when I can just SSH or VNC into these machines from my desktop.
Or maybe there's some software I might want to run permanently on a dedicated machine, rather than having it on my new laptop or my desktop, where I need to reboot into Linux or Windows for different tasks (and with the new laptop I'll sometimes want to take it out with me), so they won't be able to run any software permanently? Although if that's the only reason, a RPi would probably be just as good for this.
It's not normal for a computer to be using 99% CPU with background tasks only. I'd format and reisntall windows. If that doesn't work, there's a chance there's a rootkit infection. In that case, the laptop is a no-go for anything.
In any case, as others have pointed out, I don't see a lot of benefit of hanging with this laptop if you already have other computers. Unless you want to retire those devices and use the laptop only?
I just reinstalled Linux Mint on the whole drive and even with that it uses 60-80% of the CPU when updating. Synaptic used about 40%, right now two instances of rsync are using about 40% between them, dpkg sometimes uses 30-43%, so I'm not surprised that Windows with all its background processes and telemetry would use more.
Higher CPU usage is good. It means it's not IO bound and it will finish sooner. The problem comes when your CPU scheduler doesn't give priority to keeping the system responsive.
Linux definitely seems much better in that respect than Windows.
Windows is very bad at this. If you try to change priority of a task in Task Manager, you literally get a warning that it might make your system unstable. And they don't prioritize responsiveness of the GUI so any time a virus scan starts or Windows Update kicks off, most computers feel extremely slow. Those should both always be background tasks that should only be using spare cycles only.