When there are a lot of concurrent requests, let’s say like in the case of Flight Booking or a Popular movie this has big performance ramifications. Optimistic Lock performs badly if there’s a lot of contention at the same time because this leads to many transactions needing to be abandoned.

If the system is already running at its maximum throughput, retrying a transaction could make performance worse. The system will eventually be able to process all transactions in order, but in the meantime, some may experience delays.