The percentage of concurrency. Concurrency is a DB behavior when different transactions request to change the same resource. In the case of modifying data transactions, it sequentially temporarily blocks the right to change the data, the rest of the transactions are waiting for the access. In the case when the access for the resource is locked for a long time, then the concurrency grows (like the transaction queue) and this often has an extremely negative impact on the performance. A high contention value does not indicate the root cause of the problem but is a signal to search for it.