This section compares CPU and I/O usage across the two runs. The number of CPUs is summed for all instances and CPU usage is averaged over instances.
I/O statistics are shown for data and temp files. A high value for the single block read time (much higher than 10 milliseconds) suggests that the system is I/O bound. If this is the case, then review the total read and write times to determine if the latency is caused by excessive I/O requests or poor I/O throughput.