• Resource-efficient, fast, low-footprint, low latency.
  • Energy-, storage- and network efficient, having adequate capacity
  • Development-efficient, being easy to change (although that aspect may better be covered by #flexible)
  • Time-to-market, how efficient new features can go live


capable of producing desired results with little or no waste (as of time or materials)


The amount of computing resources and code required by a program to perform a function.


Effective vs Efficient

The words effective and efficient both mean “capable of producing a result,” but there is an important difference. Effective means “producing a result that is wanted”. Efficient means “capable of producing desired results without wasting materials, time, or energy”. The difference is that when something is effective it produces a result even if it takes some unnecessary resources to do so. When something is efficient, not only does it produce a result, but it does so in a quick or simple way using as little material, time, effort, or energy as possible. The following example sentences show how the two words are used.

  • The 200-page instruction manual was effective (=successful) in teaching the teen to repair the car himself, but it would have been more efficient (=faster and easier) for someone to show him.
  • His disorganized method of cleaning the house was effective but it was not efficient; in the end, the house was clean, but it took much longer than it should have.

The word effective puts more attention on the actual ability to produce a desired result. The word efficient puts more attention on the lack of waste in producing that result.

Britannica Dictionary

Typical Acceptance Criteria

Efficient, as we saw above, can mean several different things:

  • efficient at runtime, like defined by specific time behavior, resource consumption (e.g. energy, memory, processes, threads, network) or capacity (throughput, volume processed)
  • efficient to change or modify something within the system or its infrastructure
  • efficient concerning energy or CO2 consumption
  • efficient development processes, like short time-to-market

Scenario Response Measures from [Bass et al.]

  • The (maximum, medium, mean median) time the response takes ([latency])
  • The number or percentage of satisfied requests over some time interval (throughput) or set of events received
  • The number or percentage of requests that go unsatisfied
  • The variation in response time (jitter)
  • Usage level of a computing resource

Bass et al., 2021

What Stakeholders mean by efficient

Stakeholder (potential) Expectation for efficient
User * system produces desired results quickly
* can achieve desired results with low effort, e.g. only a few keystrokes
* system reacts immediately to commands
* low-energy consumption, e.g. long battery life
Product-Owner * dev-team can implement new features quickly
Management * high return on investment
Developer * new features can be implemented quickly
* build works quickly
* automated tests run quickly
Tester * tests run quickly
* automated tests find relevant bugs
* test infrastructure works with appropriate resources
Admin * fast deployment, installation and configuration
Domain-Expert -
Others -

Qualities tagged with #efficient

Requirements tagged with #efficient