Have you found such a tool and used it successfully?
Adobe have recently released a new profiling tool for Flash called Adobe Scout:
http://gaming.adobe.com/technologies/scout/
It's a massive improvement on the old Flash Builder profiler - it gives you a detailed breakdown of CPU time, both for ActionScript execution, and internal player functions like rendering and networking.
It's free for a trial period - you just need to register for a free Creative Cloud account. After that, there will continue to be a free basic version, with the full version available as part of a paid Creative Cloud account.