Which factor can significantly affect the performance of a CPU?

The chosen factor that significantly affects the performance of a CPU is clock speed. Clock speed refers to the frequency at which a CPU can execute instructions, typically measured in gigahertz (GHz). Higher clock speeds allow the CPU to process more instructions per second, which generally leads to better performance in running applications and executing tasks.

While RAM capacity can influence overall system performance by determining how much data the CPU can readily access without needing to swap to slower storage, it does not directly increase the CPU's intrinsic processing speed. Similarly, the graphics card, while essential for rendering graphics and gaming performance, is part of a different system component that works alongside the CPU rather than affecting its core processing capabilities. An internet connection would impact data transfer speeds and online activity but remains separate from the CPU's internal workings.

Thus, clock speed is a critical determinant of CPU performance, establishing the baseline capability of how quickly the CPU can operate, making it the most relevant factor among the options provided.