Re: Updated to MacOs Sierra, but too slow
Absolutely agree with Just_Me_D, upgrade RAM and move to an SSD if you can. These are relatively small investments, but the difference in performance will be stunning.
If you open activity monitor, can you see any processes that are constantly using major CPU (consistently anything over 10% of CPU) or hogging your Memory? This will help us give you a few additional things to try.
I doubt the following will help, but worth a shot:
Disable Transparency Effects
Go to System Preferences, then Accessibility, under Display click to enable "Reduce transparency"
Make sure you have as much free HDD space as possible
Use DaisyDisk in demo mode (purchase if you like it) to properly understand what (if anything) is hogging space
Then move or delete what you can
I find that my biggest issue every time is iOS device backups, they are never cleaned up by default and can be 20-50GB in size