Can somebody explain for what purposes there is cache property in the Resultset class?

We have used custom Decorator with Backend (Cache) to do benchmarks and faced some problems. When we use cache in models, it stores serialized resultset class with Cache property. We had Decorator in that property with whole benchmarks, so it was enough large.

I added __sleep method to the Decorator, so now cached Resultsets haven't Backend inside cache property. And Resulsets still works as expected.