What was developed to enhance a computer's video subsystem due to increased performance requirements on high-end PCs?

The Accelerated Graphics Port (AGP) was specifically developed to enhance a computer's video subsystem in response to the growing performance demands of high-end PCs. AGP provided a dedicated pathway for the graphics card to communicate with the motherboard, improving bandwidth and reducing latency compared to previous technologies like PCI. This was particularly important for applications such as 3D rendering and gaming, where high frame rates and better graphics performance are crucial.

AGP's design allowed for faster data transfers between the graphics card and the CPU, enabling more complex graphics calculations to be processed effectively. This dedicated connection meant that graphics could be rendered more smoothly and with higher detail, directly addressing the needs of users who required superior visual capabilities in their computing experience.

In contrast, the other options serve different purposes: FireWire is primarily used for high-speed data transfer between devices, USB is designed for peripheral connections and general data transfer rather than graphics, and SATA is related to storage devices and does not impact video processing directly.