I'd also recommend that the author look into tidying up the `TransactionType` field at ingest - those `ToLower` calls aren't free either, and if you've got cont

I'd also recommend that the author look into tidying up the `TransactionType` field at ingest - those `ToLower` calls aren't free either, and if you've got control of the system writing the data it's easier to just store a consistent case. Failing that, `EqualFold` may be worth looking at. It expresses the same intent, dunno if it's more or less efficient.