You can use pipeline profiling to identify opportunities to improve system performance by optimizing pipelines.

Pipelines separate the implementation of processes into a series of discrete processors, each typically responsible for a single operation invoked by one or more components somewhere within the system.

Sitecore 8 pipeline profiling id disabled by default. To enable pipeline profiling, rename the /App_Config/Include/Sitecore.PipelineProfiling.config.disabled to Sitecore.PipelineProfiling.config

URL: https://domainname/sitecore/admin/pipelines.aspx

This provides information about each pipeline number of times execution or invoked by individual process or within sitecore and wall time is the amount of milliseconds took during all invocations of the pipeline.

Screenshot – showing Pipeline Profiler:

Screenshot – showing Rest Pipeline Profiler: