There are several load testing tools that attempt to determine the behavior of systems, networks and servers when an application is concurrently used by a large number of users. Any good testing tool should help you to get a comprehensive picture of end-to-end system performance, test new and upgraded applications against predetermined performance requirements and identify and isolate issues in the application. The identification of application bottlenecks makes it easy to prevent problems that may occur when the application is used in the real world. Testing reduces downtime once the application goes live. The choice of performance testing tool would depend upon the budget and requirements. LoadRunner is a popular load testing tool by Hewlett-Packard that allows automated testing or the automatic recording of performance.

Why use LoadRunner for Load Testing?
LoadRunner allows the tester to generate the script with one click through a friendly GUI. Depending upon your requirements, you can make necessary changes in the script at a later time.
LoadRunner works on native monitors and is not required to be installed on the server being tested.
LoadRunner can perform load testing with an enormous number of virtual users.
Since LoadRunner emulates the real world with virtual users, load testing can be managed single-handedly.
All the virtual users can be monitored effectively on a single computer, substantially reducing hardware requirement.
ANSI C is the programming language that LoadRunner uses by default. However, LoadRunner can work with any technology, including VB, ERP and Java.
LoadRunner can match any system, including web servers, streaming media servers and web application servers.
LoadRunner supports a large number of protocols.
The user friendly interface makes it easy to analyze detailed reports. Specific colors assigned to graphs and charts, in the analysis section, increase result visibility.
LoadRunner promotes easy correlation.
Hewlett-Packard provides comprehensive tutorials and offers excellent tool support.

Shortcomings of LoadRunner for Load Testing
LoadRunner is costlier than most automatic testing tools.
If the testing is a little complicated, with different scenarios, then the script would have to be created. This requires a programming mindset. You may need to hire a programmer, which could add to your costs.