How to locate Performance Bottlenecks at Low CPU Utilization?

Bottlenecks at Low CPU Utilization: If your site has low CPU utilization when it is achieving maximum throughput, the bottleneck is likely either:

• Database limited (if database output is maxed out); see Checking for Database Bottlenecks
• Disk I/O limited (if I/O output is maxed out); see Checking for Disk I/O Bottlenecks
• Network I/O limited (if I/O output is maxed out); see Checking for Network-Limited Problems
• Database or I/O activity in a synchronized method (if database or I/O output is not maxed out); see System Resource Bottlenecks

If your site is in this situation, CPU profiling tools like OptimizeIt are not that useful. Thread dumps taken while the system is under load can give you better information.