Easy: convert them to Linux!
That ain't as true as it used to be... Speaking of active variations...
It's kinda been a thing for me, trying to resurrect some of the cool notebook stuff from even the early Win7 era - Finding a dist small enough to run fast on them is a bit of a fool's errand.
Now, I am speaking of something prepared and maintained... and actually functional - Not Damn Small or any other dist that is basically bare... I can start there and roll my own, I know.... But I don't care enough to do all that.
A current, tight, lightweight Linux is a bit of a unicorn.