Linguistics is falling into the clutches of the politically correct these days, which leads to the "all languages are equally efficient" doctrine, so as not to offend national egos.

However, they aren't. There are objective criteria to compare the efficiency of languages, for instance: economy, redundance, derivation, and consistency.

Economy: The ability to express more information with less words or with shorter words. The benefit: you save time.

Redundance: The ability to distinguish words in noisy environments. This quality is usually in conflict with the economy quality. Languages with shorter words lose more information for each second of interruption. Example: a faulty cell phone communication occurs while an English speaker says: "Ann ate eight cakes" and then when a Spanish speaker says: "Ana se comió ocho pasteles" compare information lost by suppressing one syllable in the verb and the object: "Ann ? eight ?" versus "Ana se ?mio ocho pas?les" The Spanish speaker will easily reconstruct the incomplete words, the English speaker will have a harder time, because he has whole words. Inversely, under normal circumstances, the English speaker will finish the sentence before, saving time.

Derivation: The ability of a language to create new words. Take for instance the Greek philánthropos ("lover of humanity") of course English could have shunned the Greek "philanthropist" and said "humanity lover" but Greek can go further, and say philanthropikós ("pertaining to a humanity lover"), philanthropikótes ("the quality of being a humanity lover") philanthropô ("to humanity-love") philanthropikôs ("humanity-lovingly") participles: philanthropôn, philanthropoúmenos, philanthropésas (who humanity-loves, who is humanity-loved, who humanity-loved) to just name a few. Languages with more derivation capabilities give their speakers the ability to name complex concepts more easily, facilitating complex thought.

Consistency: The quality of having rules and following analogy principles. A language with few irregularities will be more easily learned by foreigners and cause less semantic confusion. For instance the English verbs "to lie" and "to lay" cause confusion even among English speakers, let alone foreign students.

TL;DR Comparing the efficiency of languages is politically incorrect, but it can be done.