New Relic vs. Vector vs. Skylight

New Relic is the all-in-one web application performance tool that lets you see performance from the end user experience, through servers, and down to the line of application code.

Vector provides a simple way for users to visualize and analyze system and application-level metrics in near real-time. It leverages the battle tested open source system monitoring framework, Performance Co-Pilot (PCP), layering on top a flexible and user-friendly UI. The UI polls metrics at up to 1 second resolution, rendering the data in completely configurable dashboards that simplify cross-metric correlation and analysis.

Skylight is a smart profiler for your Rails apps that visualizes request performance across all of your servers.