How to get a faster speed when using multi-threading in python

Now i am studying how to fetch data from website as fast as possible. To get faster speed, im considering using multi-thread. Here is the code i used to test the difference between multi-threaded and simple post.

import threading
import time
import urllib
import urllib2


class Post:

    def __init__(self, website, data, mode):
        self.website = website
        self.data = data

        #mode is either "Simple"(Simple POST) or "Multiple"(Multi-thread POST)
        self.mode = mode

    def post(self):

        #post data
        req = urllib2.Request(self.website)
        open_url = urllib2.urlopen(req, self.data)

        if self.mode == "Multiple":
            time.sleep(0.001)

        #read HTMLData
        HTMLData = open_url.read()



        print "OK"

if __name__ == "__main__":

    current_post = Post("http://forum.xda-developers.com/login.php", "vb_login_username=test&vb_login_password&securitytoken=guest&do=login", \
                        "Simple")

    #save the time before post data
    origin_time = time.time()

    if(current_post.mode == "Multiple"):

        #multithreading POST

        for i in range(0, 10):
           thread = threading.Thread(target = current_post.post)
           thread.start()
           thread.join()

        #calculate the time interval
        time_interval = time.time() - origin_time

        print time_interval

    if(current_post.mode == "Simple"):

        #simple POST

        for i in range(0, 10):
            current_post.post()

        #calculate the time interval
        time_interval = time.time() - origin_time

        print time_interval

just as you can see, this is a very simple code. first i set the mode to "Simple", and i can get the time interval: 50s(maybe my speed is a little slow :(). then i set the mode to "Multiple", and i get the time interval: 35. from that i can see, multi-thread can actually increase the sp