Optimize models containing lists of other models

[Jonxslays]

Currently some of our models contain a list of other models i.e. MetricLeaders , PlayerGainsData, SnapshotData, and maybe more?

Those lists need to be filtered or otherwise iterated in order to access the data inside.

It would be nice if these items were actually a mapping with the keys being Metric's, and the values being the models themselves. This would allow for constant time lookups and increase performance for end users.