Bandwidth is a shared resource so using too much can limit the performance of the entire system in unpredictable ways. For example, graphics memory is shared with application memory so high bandwidth usage by the GPU can degrade CPU performance.

Accessing external memory requires a lot of power so reducing bandwidth usage reduces power consumption.

Accessing data in cache reduces power usage and can increase performance. If your application must read from memory a lot, use techniques such as mipmapping and texture compression to ensure your data is cacheable. See Use mipmapping, and see Use texture compression.