What make/model computer or what are the system specs?
First thing that comes to mind is that you might have a system with less than 8GB RAM. I had a issue like this with a system with 4GB RAM running Windows 10 64-bit with all RAM in use and constant hard drive activity as it was paging a lot in Virtual Memory on the Hard Drive. I upgraded to 8GB RAM and the system acted like before the update nice and quick.
When you refer to software update I am assuming your meaning Windows Updates.
Disabling the Windows 10 updates will make your system vulnerable to exploits and other security issues due to not being properly patched, so it might be better to find the cause of the sudden slowness and fix that vs just rolling back to previous Windows 10 and version locking it.
Additionally if your system is running on less than 8GB RAM and this issue is happening and you cant upgrade RAM or dont want to upgrade the RAM, then you could try disabling the Super Fetch Service which would make Windows 10 not fully populate your systems memory all the time with frequently used data and the only stuff that will be in RAM is what needs to be vs what windows thinks you might need fast access to.
https://www.technipages.com/windows-enable-disable-superfetch
