What Framework would be the fastest to build a social network app?

[Henrik41]

Let say I want to build an app like TikTok (I know it's unrealistic).
Database used : Mysql
Frontend: who cares (probably swift/kotlin)
Server/Side: ?????

So I am guessing the flow would be:

User -> My Server -> Database -> My Server (serialization) -> JSON sent to User

I know rails but it's really slow.
However -> Login is already done/ MVS Architecture done/ Push notification server done in rails

So what framework would you personally use to build such an app??