Web Application Performance Improvement

When a web application is accessed by few users the performance may not be a huge problem but as the numbers of users grow it might bring your application to a halt if not designed properly with scalability in mind.It's always good to start out by profiling the application first. The profiling can give you insight on the piece of code that is expensive. A piece of code that is expensive might not necessarily be the main culprit. Always look for the piece of code that is extensively called. For example you might have one method that takes 2 seconds to run and then the other method that takes 200 ms. First intuition might be to make the first method efficient. But it might be the case that your application calls the method 1 or 2 times whereas it calls the second method thousands of time. In this case it's always good to optimize the second method.

Connection Pooling

If your application accesses database a lot make sure you are using connection pooling. And also consider using Stored Procedure if you need to filter results or make multiple requests to the database in the same code path.

Caching

If results can be reused across multiple requests, it's always a good idea to employ cache.

Compression

Make sure server supports compression and is using it to send results. This decrease communication time.


Clustering

Use server cluster for your application.

Resource contention

Minimize resource contention because if lot of requests are competing for same resource they degrade performance and hinder scalability. For example servlet is a shared resource and having synchronized method in servlets may cause scalability problems.

Memory Usage

Watch memory usage of your applications and try to reduce unnecessary memory usage.Use of large amount of memory might trigger garbage collector frequently which uses precious CPU time which could have been used for serving users.