faster-loop.js

var reference = my.complicated.object.reference;

for ( var i=0; i<100; i++ )
{
  doSomething( reference, i );
}

fastest-loop.js

var
reference = my.complicated.object.reference,
i = 100;
while ( i-- )
{
  doSomething( reference, i );
}

slow-loop.js

for( var i=0; i<100; i++ )
{
  doSomething( my.complicated.object.reference, i );
}