If you are experiencing performance issues, which command is recommended to use first?

The recommended command to use first when experiencing performance issues is top. This command provides a real-time, dynamic view of the system's processes, along with their resource usage, including CPU, memory, and swap utilization. By using top, you can quickly identify if specific processes are consuming excessive resources, which can be crucial for diagnosing performance bottlenecks.

While tools like hdparm, iostat, and vmstat offer valuable information about disk performance, I/O statistics, and memory usage respectively, they are generally more specialized. A general overview provided by top allows for quicker identification of issues that might be causing the system's sluggishness, making it an ideal starting point in troubleshooting performance problems.