seriously slugging after clean install

..at this point we're looking at actual, not potential..

Hi, sorry, you need to organise this by showing the highest disk use topmost and highest CPU use topmost please as I said along while back.

Open the task manager, click on Disk, then do the screenshot.
Likewise,
Open the task manager, click on CPU, then do the screenshot.

Thanks!

Following that, you will probably need to do this:
Clean Boot - Perform in Windows 10 to Troubleshoot Software Conflicts - Windows 10 Forums

accidently performed a full recovery which took the laptop back to Windows 8.1 (with 10 downloading in the background) and this seems to have made a massive difference.

Speed seems reasonable, hard drive activity is definitely lower and it seems overall a lot more "buttery" - could it all really have been due to a corrupt install of Windows 10 ?

Hi, glad you're back to a working PC.
While many things are possible, I'd say unlikely.
Bear in mind that in upgrading to Win 10, then
- you replace the whole OS (but don't update your programs)
- you replace all the drivers

So you
- have possible conflicts between older progs and the OS
- have possible incompatibilities between hardware and drivers
- possibly experience odd bugs with a new combination of software from various sources

Some people have experienced high CPU use, slow systems after upgrading to Win 10 for a variety of reasons.
Some experience latency issues not present in Win 8 which slows their system.

Unfortunately with yours we lack the evidence to start to identify the cause.

Here's what I'd suggest. If you still want to use Win 10, I'd suggest
a. make a disk image of your Win 8 (which you should routinely anyway as a system backup)
b. clean install Win 10 and experiment with getting it working properly.
That eliminates the effect of anything inherited from Win 8.

(You can revert to your Win 8 any time by restoring your image).