Apparatuses and methods related to port arbitration of a memory system are described. A memory system can receive a first number of transactions and a second transaction from a first traffic stream and a third number of transactions and a fourth transaction from a second traffic stream. The memory system can process the first number of transactions at least partially concurrently with the third number of transactions. Responsive to a total quantity of transactions of the first number of transactions and the second transaction being at least a threshold quantity of transactions, the second transaction can be processed by the memory system and, subsequent to processing the second transaction, the fourth transaction can be processed by the memory system.