Has anyone observed drastic speed differences using a concurrent user in your Sandbox vs. Production? I am running a process with 4 threads processing sales orders. This process pulls all of the sales order's information, work orders, and two custom records. In Sandbox, which was just refreshed from production, I see it taking a few seconds to retrieve and update the status on a sales order. In production this process takes, on average, 1 minute per work order on the sales order. The total orders I can process in 24 hours concurrently in production takes about the same time as when it was single threaded, while sandbox is 4-5x times faster.