Previously answered questions here said that this was the fastest way:
//nl is a NodeList var arr = Array.prototype.slice.call(nl);
In benc
The most fast and cross browser is
for(var i=-1,l=nl.length;++i!==l;arr[i]=nl[i]);
As I compared in
http://jsbin.com/oqeda/98/edit
*Thanks @CMS for the idea!