What is a common reason for computer performance issues?

Having too many open applications is a common reason for computer performance issues because each running application consumes a portion of the system's resources, including RAM and CPU power. When multiple applications are open simultaneously, they can compete for these resources, leading to slowdowns, freezes, or even system crashes. This resource contention can significantly degrade the user experience, making the system feel sluggish or unresponsive.

In contrast, a high-quality graphics card generally enhances performance for graphical tasks; a fast internet connection does not directly affect local computer performance but improves online activities; and updated software, while occasionally causing issues if not compatible, typically aims to improve overall performance and security. Thus, it's clear that the number of open applications is a critical factor in maintaining optimal computer performance.