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So I don't see the perf concern of .slice.call(arguments), use it if u need to slice up the arguments object:
var args = slice.call(arguments),
var first = slice.shift(); // remove first
So basically use it when you need it and not when you don't :D
You should also mention that by simply using the arguments object, engines may disable optimizations which will result is perf hit for the specific function. See issue 19.
Any PR arising from this? I'm helping to maintain now so stuff is being merged.