Creating and setting up formatter objects is an expensive operation indeed, so I'd start with reusing your formatter objects since they are the same on each function call. So either make them static variables or instant variables in your data source class and create the following way.
Firstly, you are using two different identifiers: CustomCellIdentifier and BanciHistoryCellIdentifier.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.