Latency may not actually be the result of a slow service from the DBaaS provider. There are other factors that are out of the control of the software layer and simply deal with the actual hardware.
Also, you cannot compare speed of the local network against a data-centre, as the local network will always win, simply because:
- It is physically closer to the end-user
- There is less amount of traffic within the local network
Being physically close to the source of whatever you are rendering is vital for speed, that is why the trade-servers of big investment firms that trade in micro/milliseconds are literally sometimes next to the stock exchange buildings.
The best way to overcome latency is to use the local network, as there is no way you can optimize to match the speed of it from a data-centre (unless you build one next to the offices of the end-user).