One thing you don't mention is how much RAM and how much storage you have.
The two things that effect the speed of a particular computer to a noticible extent are faster storage (moving from a rotational HD to an SSD, or to a faster SSD) and more RAM. The latter depends on how you use your Mac. If you keep lots of applications open and run applications that use lots of RAM (graphics, video and sound editing spring to mind) then more RAM will likely help.
Your Mac, however is configured from Apple and not upgradeable so those avenues are closed to you. That severely limits your ability to enhance the performance of your Mac via hardware solutions.
You can certainly try other ways of reinstalling the o/s and migrating the settings and doing so MIGHT have a small impact on the speed of your Mac, but it is unlikely you will gain much from those exercises.
I note that this Mac has either 2GB or 4GB of RAM. 4GB might be barely enough (depending on your use) but if you have a 2GB model... well I'd probably sell it and get a newer one with 8GB of RAM. Again, a personal opinion, it might work for you but that is not a lot by today's standards.
Personally, I would recommend a couple of things.
- A system cleaner app. I use Onyx that basically cleans out all the caches and runs all the maintenance scripts. It can help with system slowness, depending on where the slowness is coming from. I run Onyx every few months just to keep my bits and bytes sparkly clean!
- Check your startup items (System Preferences > users & Groups > Login Items) and remove them. You'll lose their functionality but gain back some RAM and CPU cycles.
There may also be things that start up with the system that are not there in login items. A/V apps, do this as do VPN apps and also MS Office. These apps have things running in the background at all times. Some you may want to remove. You'll have to look at the developer's website for instructions how.
But regardless of all of this and even if you try the alternative clean reinstall you mentioned I doubt that any of them will result in a substantial improvement.