Why file read is faster on reading again?

Question

SIZE = 1<<16
def justread(file):
    with open(file, \'rb\') as f:
        while f.read(SIZE):
            pass

The first time I run t

Answer 1

The operating system caches the file in memory upon the first read, and the second time it is read from memory instead of from hard disk. Of course memory is much faster.