The SP2010 Developer Dashboard allows developers to review object model calls, database queries, web part events – and the timings for these various happenings.

The following code enables the dashboard:

SPPerformanceMonitor SPPerfMon;
SPPerfMon = SPFarm.Local.PerformanceMonitor;
SPPerfMon.DeveloperDashboardLevel = SPPerformanceMonitoringLevel.On;
SPPerfMon.Update();

The following code turns it off again:

SPPerformanceMonitor SPPerfMon;
SPPerfMon = SPFarm.Local.PerformanceMonitor;
SPPerfMon.DeveloperDashboardLevel = SPPerformanceMonitoringLevel.Off;
SPPerfMon.Update();