Qualify the hardware platform

Obviously the fit of a hardware platform needs to be validated for a specific application context. The INtime Graphical Jitter Display may be part of the validation activities.
 
It measures the deviation (in microseconds) of response to kernel timer events. It is a good indication of delays your application may experience during execution.
Run this tool “long enough” to cover all possible load scenarios including external interrupts etc.
As with any other statistical measures, the result can not guaranty a WCET (worst case execution time). It just provides a confidence level, and you need to judge if you feel the confidence level is sufficient for your application.
A detailed measure of your applications’ actual timing can be taken with INScope, a tool that captures and analyzes trace information on the system level (e.g., thread switches, system calls, interrupt handling) and on the application level (API for high-level tracing in your application).