Effectiveness and Efficiency

Efficiency or capacity to get work done in less amount of time or efforts and effectiveness the capability to produce desired results are terms very often used and confused in our day to day life.
Many a times different idioms are used to highlight efficiency or Lack of it.
Here are a few idioms on efficiency.

acid test	To refer to something as' the acid test' means that it will prove how effective or useful something is. The training course was very interesting but the acid test will come when I start my new job.
(whole) bag of tricks	If you use your (whole) bag of tricks to do something, you try (all) the clever methods you know in order to succeed. Let's call on George and his bag of tricks; maybe he can help us solve the problem.
on the ball	If you are on the ball, you are aware of what is happening and are able to deal with things quickly and intelligently. We need someone who is really on the ball to head the fund-raising campaign.
to the best of one's ability	When someone does something to the best of their ability, they do it as well as they possibly can. I felt nervous all through the interview, but I replied to the best of my ability.
kill two birds with one stone	If you kill two birds with the one stone, you succeed in doing two things at the same time. By studying on the train on the way home, Claire kills two birds with one stone.
take the bull by the horns	To take the bull by the horns means that a person decides to act decisively in order to deal with a difficult situation or problem. When the argument turned into a fight, the bar owner took the bull by the horns and called the police.
can't hold a handle to	If one person can't hold a candle to another, they are much less competent or do not perform as well as the other. John is very intelligent but he can't hold a candle to his brother Paul when it comes to sports.
chase your (own) tail	Someone who is chasing their (own) tail is spending a lot of time and energy doing many things but achieving very little. He's been chasing his tail all week collecting data but the report is still  not ready.
like clockwork	To say that someone or something goes, runs or behaves like clockwork means that everything happens exactly as expected. Meals are always served on time.  In their home everything runs like clockwork.
cut the ground from under feet	When someone cuts the ground from under another's feet, they do something which weakens their position or spoils their plans. When we launched the new product, we cut the ground from under our competitors' feet.
dab hand at something	If you're a dab hand at something, you're very good at doing it. Why don't you call Suzy? She's a dab hand at organizing barbecues.
deliver the goods	If a person delivers the goods, they do what is expected of them or what they have promised to. Let's hope that new whiz-kid the boss hired can deliver the goods!
do nothing by halves	When a person does everything they are engaged in completely and thoroughly, they are said to do nothing by halves. When she cooks, it's a four-course meal - she does nothing by halves!
do the trick	If something does the trick, it does exactly what is needed, or achieves the desired effect. Another coat of paint should do the trick.