Performance regression in eachSeries after 1.0.0

[goldfire]

I've noticed that the speed of eachSeries has dropped significantly since 1.0.0. I've tested all versions since and the problem persists. I've created the following fiddles to demonstrate the issue:

1.0.0 - http://jsfiddle.net/nawojL7o/
1.4.2 - http://jsfiddle.net/pyw6tdp2/

[aearly]

We added a nextTick between each step of iteration in eachSeries to a avoid stack overflows. We're going to remove it in 2.0, because it does impact performance, but it also does change the behaviour slightly.

[megawac]

Closing as dupe of #696