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#21
I must admit I'd try that number 2 (backup and clean install) first.
I don't see there's much to lose by trying it, except the time taken to do the clean install and reinstalling enough software to see if the speed is liveable with. If not then just restore the backup and shop for a new computer.
I'm currently typing this on a very nearly 10-year old laptop which has given good service and running Windows 10 32 bit. Admittedly I just use it for basic tasks, but it does the job.