open("","r")与open("","rb")的效率区别

fd = open("C:\Users\william\Desktop\dup_file - Copy (3).txt","r")
for i in fd:
print i

耗时 25.6074296742s

fd = open("C:\Users\william\Desktop\dup_file - Copy (3).txt","rb")
for i in fd:
print i

耗时 60.840389834

有文章提到说在windows系统中，要加上rb，否则代码会很慢，但通过上面，发现rb明显更慢。