Is there a difference between efficiency and performance? “Performance” feels like it's specifically about execution speed; “efficiency” could be about memory or disk space or other resources.
In any case, the four questions tagged efficency must be retagged, to fix the spelling. Should they be retagged to efficiency or performance? Should efficiency and performance be synonyms?
Well, I'm not too concerned either way, but I'll vote for making efficiency a synonym of performance
Efficiency is about appropriateness of resource consumption. Performance is about speed of execution. They are similar, but slightly different, concepts. Using the minimum CPU and memory to get a particular job done within the time constraints may be the most efficient way to do the job, but it won't provide the highest performance.
Most likely, people are tagging questions efficiency when they mean performance. There aren't that many real questions about efficiency.
Efficiency can be about memory usage, or power consumption, but performance can be used for that purpose too, while most questions are about speed of execution.
