fast way to read big file line by line

fast_io.py

from functools import partial
import codecs

def fast_read(name, bytes):
    with codecs.open(name, 'r', 'utf-8') as f:
        prev = ''
        f_read  = partial(f.read, bytes)
        for text in iter(f_read, ''):
            if text == '':
                return
            if not text.endswith('\n'):
                text, rest = text.rsplit('\n', 1)
                text =  prev + text
                prev = rest
            else:
                text =  prev + text[:-1]
                prev = ''
            for l in text.split('\n'):
                yield l
  
def normal_read(name):
     with codecs.open(name, 'r', 'utf-8') as f:
        for l in f:
            yield l