As we have designed and implemented the Didget Management System, we have done a good job so far at adhering to these basic principles:
1) No dependencies. We purposely stayed away from using any thing that may cause dependency issues down the road. We don't use .NET. We don't use third party libraries other than the standard C++ libraries. Our browser application uses Qt but the manager itself does not.
2) Take full advantage of CPU cores/threads. We want our code to run much faster on a CPU with more cores. Large individual operations are often broken up into multiple pieces and run in parallel using separate threads. We are not just running multiple queries simultaneously like many database servers (we do that too), but we can run a single query faster when more cores are available.
3) Use thread-safe code. Because we do so many things at the same time, we want to allow multiple operations on the same set of data to safely run in parallel. Data integrity is very important whether running many separate queries simultaneously or when many threads are running different parts of the same query.
4) Be operating system independent. We want this code to run equally well on Linux, Windows, or OSX. All operating system calls are confined to a single 'Kernel' module which is easily ported to other operating systems.
5) Be faster than anything else. Use things like maps, hash tables, and very fast algorithms written in efficient C++ code to do everything. No interpreted code.
6) Re-use code whenever possible. Often the same function can be used to manipulate a dozen or so different kinds of Didgets. When we fine tune something, it often improves performance in multiple areas.