It uses steem to do most RC type things. Individual transactions can be queued and executed, 1 per block. Network executable contracts(where processing is cheaper than verifying... auctions, and equity deposits, etc) might not have a transaction limit due to this. Custom/distributed contracts will likely have a 1 minute lag time between executions, but this is per contract. The DEX should process transactions in 1 block or 1 minute to up to 3 minutes... depending on the complexity.