OK Over a week and you haven’t responded to @Incanus basic query, 
~ which phone do you want to ‘speed’ up.
Then
- are you using the deafult setup
- have you tried safe mode to see if any of your apps are an issue
- How about a factory reset which you will have to do to try out others and of course to compare.
As each owner uses their phone differently what may seem to be a faster OS to one may not be the same to another.
So in which respect do you find A11 slow. I have 2FP3s and have no problems.
I suggest you consider trying some with the basic setting in each case for a few days or a week.
I use the default OS with apps removed by adb, which may help.