Recently i have developed a billing application for my company with Python/Django. For few months everything was fine but now i am observing that the performance is dropping because of more and more users using that applications. Now the problem is that the application is now very critical for the finance team. Now the finance team are after my life for sorting out the performance issue. I have no other option but to find a way to increase the performance of the billing application. 
So do you guys know any performance optimization techniques in python that will really help me   with the scalability issue
Guys we are using mysql database and its hosted on apache web server on Linux box. Secondly what i have noticed more is the over all application is slow and not the database transactional part. For example once the application is loaded then it works fine but if they navigate to other link on that application then it takes a whole lot of time.
And yes we are using HTML, CSS and Javascript
before you can "fix" something you need to know what is "broken". In software development that means profiling, profiling, profiling. Did I mention profiling. Without profiling you don't know where CPU cycles and wall clock time is going. Like others have said to get any more useful information you need to post the details of your entire stack. Python version, what you are using to store the data in (mysql, postgres, flat files, etc), what web server interface cgi, fcgi, wsgi, passenger, etc. how you are generating the HTML, CSS and assuming Javascript. Then you can get more specific answers to those tiers.
Optimization Techniques in Python