Converting a string containing whitespace-delimited numbers to a list of numbers

Suppose I have a string str that contains only whitespace-delimited real numbers:

str = " 0\t1.46604\t1.44829\t12.0546\t1.57075\t1.64044\t12.0489\t1.58142";

I would like to convert str to a list of real numbers. One way to accomplish this is to split the string using StringSplit and then Map the function ToExpression across the resulting list:

Map[ToExpression, StringSplit[str]]

which gives the correct output:

{0, 1.46604, 1.44829, 12.0546, 1.57075, 1.64044, 12.0489, 1.58142}

But, is there a cleaner or more efficient way to do this? I will be converting about 100,000 strings str -- each of which are approximately the same length as the example str above -- which will be read as records from a text file (i.e., using OpenRead and Read), so it would be nice if the method is relatively efficient. Thank you for your time!