swap out the drive for a SSD type. I did this on a Win7 netbook and it didn't make a vast difference
I suspect that the SSD in that situation was held back by the processor and RAM - netbooks are not noted for their computer performance. In my experience, with a decent processor and adequate RAM, replacing a spinning disk (particularly a 5400 RPM) with an SSD makes a vast difference to performance.
What's the spin speed of the disk in question? 7200 or 5400? What version of SATA - I assume that the system is SATA, not PATA? The performance problems you describe sound too extreme to be just down to RPM and older SATA - it sounds as if there's a physical problem - e.g. lots of bad sectors - or a logical problem, e.g. cross-linkages. Another problem could be excessive paging, but with 8GB RAM there would need to be a massive memory leak or a memory hog.You should be able to see the SMART diagnostics for the disk, either through the disk manufacturer's application or a 3rd party diagnostics tool - but you need to understand what the figures mean and what they are telling you.
Getting an SSD would give you a number of options - clone the existing disk to see if the SSD solves any physical problems, or alternatively build a fresh Windows 8 installation and see what the performance is like. Installing Win8 would give a like-for-like comparison, but you might prefer to install Win 10 sooner rather than later - Win 8 goes EoL on January 10, 2023, so an upgrade / replacement is only a bit over 2 years away.
I have to use Win 10 for work - my home PCs run Linux Mint, like you - and I find it reasonable, although the look and feel of Win 7 is still better (IMHO). There's a lot of niggling annoyances with Win 10, such as missing accessories, inability to configure various UX preferences etc. (and Office 2016 is NOT an improvement over 2010!) I never used used Win 8, but I loathed the Server equivalent (Server 2012). Charms bar on a server, my @rse!
SD