Slow performance of POS tagging. Can I do some kind of pre-warming?

I am using NLTK to POS-tag hundereds of tweets in a web request. As you know, Django instantiates a request handler for each request.

I noticed this: for a request (~200 tweets), the first tweet needs ~18 seconds to tag, while all subsequent tweets need ~120 milliseconds to tag. What can I do to speed up the process?

Can I do a "pre-warming request" so that the module data is already loaded for each request?

class MyRequestHandler(BaseHandler):
    def read(self, request): #this runs for a GET request
        #...in a loop:
            tokens = nltk.word_tokenize( tweet)
            tagged = nltk.pos_tag( tokens)