Mobile and embedded systems must balance compute power, battery life and cost. This means mobile platforms are constrained in terms of available resources such as:
Desktop systems do not have these limitations so application developers have much more compute resources to utilise.
Mali GPUs are typically used in mobile or embedded systems so it is important to be aware of these differences if you are porting a graphics application from a desktop platform.
Some graphically rich applications are initially developed for desktop platforms and are later ported to embedded or mobile platforms. The reduction in available resources means that the application is unlikely to work at the same performance level as it does on the desktop platform.
Optimization enables your application to get closer to the performance level it achieves on a desktop platform.