This is part 1 of a multiple part series on web performance improvements. The Introductory blog can be found here. In introductory post we discussed importance of software development keeping performance performance at center. In this part we will discuss which part affect web application performance the most? Where we can start the performance improvement activity to get maximum output?
Any web application performance improvement activity is a series of calculated tasks. We need to first identify where we can achieve the greatest improvements. There are three main places to consider:

• Frontend
• Backend
• Databases

Though we can group the backend and databases in same group but just for simplicity I have grouped them separately. In case of web applications the performance is always measured with respect to user response time. Whatever performance improvement tasks we do should result in improved user response time. If not then we should re-visit our performance improvement strategy again. Due to many reasons, some of them given below, it is clear that first place to focus is frontend to drastically improve the performance of the web application.

• First and foremost, generally, the time and resources required to implement the frontend changes is less as compared to others. Improving the backend performance may require change in architecture, code, data retrieval logic etc. These tasks may take longer time than expected.
• If we could cut the backend response time by 40-60%, this will reduce the overall end user response time by 10-20%. But if we could improve the frontend performance by 40-60% this could result in reduced end user response time upto 40-50%. Many sites likes Google, MSN, Yahoo, Ask etc has proved this point.

Following figure is a snap-shot of Y-slow recordings for a page in a website.

In coming blogs we will go through a series of steps that will help us understanding the performance pitfalls and how to improve them.