Node Performance: Audit long closures

[kriskowal]

All closures should be short thunks for methods, such that those methods get tread often enough to be optimized by V8.

via #800

[Raynos]

We should also avoid closures where possible.

[jcorbin]

Also another aspect is simply depth of closure nesting, preferably there should be none, but this isn't always possible... a hard limit should be around 2 or 3 in an extreme case.