Testing is an ongoing process. By the time you reach the premastering stage you should be positive that your text is flawless, the images and sounds look and sound perfect, and the overall application is just as you want it. Performance testing is particularly important in multimedia applications, especially where you load images and sounds—perhaps even with some degree of synchronization.
There are two main ways to test the performance of your application: you can press a disc and run it, or you can run the application in a simulated CD-ROM environment. Both methods have their advantages. Some premastering systems offer you a choice. For a nominal fee they will create a one-off disc for you to test until you are totally satisfied. If you have extensive testing to do, this is a good approach as it won't tie up a lot of expensive equipment at a high hourly rate.
Premastering systems can often simulate a CD-ROM environment by storing the data on a large hard disk that has had its access time and transfer rate reconfigured to simulate that of a CD-ROM. The advantage of simulation is that you can usually do some fine-tuning. If you find a problem area, you can make corrections and repeat the test.