On the BitShares DEX your trades execute in seconds, just like any centralized website interface. However, unlike centralized exchanges, there can be no high-frequency trading, front running, or hidden orders. Traders are thus on a level playing field. On Wall Street, traders go to great lengths to get as physically close to the exchange systems as possible, because their trading bots make decisions so quickly. A decentralized exchange is location-neutral, giving everyone an equal opportunity. You can also setup a local API node - literally bringing the exchange to you.