What is the most likely cause of a server becoming consistently slower until reboot?

A server that becomes consistently slower until it is rebooted is often experiencing a memory leak in one or more of its services or applications. A memory leak occurs when an application uses memory but fails to release it back to the operating system after it has finished using it. Over time, these leaks can accumulate, causing the system to exhaust available memory resources, leading to decreased performance as the server struggles to manage the limited resources effectively.

When a service or application continuously consumes more memory than it needs, the remaining available memory decreases, causing the server to slow down. Rebooting the server typically clears all memory and resets the state of running applications, temporarily alleviating the performance issues until the leaks build up again.

While performance misconfiguration can cause issues, they would typically be more immediately apparent and not necessarily progress in the same gradual manner associated with memory leaks. Incorrect server resource specifications might lead to performance problems from the start, and corrupted application files could cause erratic behavior or crashes, but they would not specifically result in a gradual slowdown linked to memory usage. Thus, the most fitting explanation for the described issue is indeed the presence of a memory leak within an application or service.