calculate efficiency

[remote narwhal]

I'm watching a video and I'm trying to understand why it's 40% faster comparing the speed of two numbers.
116ms is the difference between 290ms, the new speed, vs previous speed, 409
1 - 290/409 is 30% difference, so that makes the new record 30% more efficient. Why is efficiency 40%?

[mighty roost]

,calc (1/290) / (1/409)

[ocean grail]

Result:

1.4103448275862

[mighty roost]

if it takes 290 ms you're doing 1/290 of the work each ms

divide larger efficiency by smaller and you see the increase