Efficiency can be doubled in English.
Efficiency can be translated to "efficiency" in English, and to express an increase in efficiency by a factor of two, you might say:
- "Two-fold increase in efficiency" - "Efficiency doubled" - "Efficiency enhancement by a factor of two" - "A 100% increase in efficiency" - "Efficiency improved by two times"
- "Two-fold increase in efficiency" - "Efficiency doubled" - "Efficiency enhancement by a factor of two" - "A 100% increase in efficiency" - "Efficiency improved by two times"