Do you have a Fusion drive or flash storage, or is it a mechanical drive? If it is a mechanical drive, I doubt you will see much if any improvement.
In fact, generally speaking, upgrading the OS is not a good solution to a computer that is exhibiting sluggishness. It's better to try to isolate the root cause and address it rather than hope upgrading the OS will fix something.
Have you tried booting into safe mode to see if the issues are resolved? That would point you towards something you have installed if it improves in safe mode. Also, creating another user and checking to see if the problems are the same for the other user is another way to get a handle on whether this is due to something you installed.
You can also check the condition of the disk and memory with various utilities, in case degrading hardware is the cause.