With the help of IDE integration: use the "Profile" action from within your IDE, like you do "Run" or "Debug".

You can profile applets running inside a browser with Java Plugin installed.

Please add the appropriate -Xrunyjpagent (Java 1.3./1.4) or -agentlib:yjpagent (Java 5 or newer) option in "Java(TM) Plug-in Control Panel", on the "Advanced" tab, in the field "Java Runtime Parameters", and modify the appropriate environment variable, as described in the Enabling profiling manually section.

On Windows, "Java(TM) Plug-in Control Panel" is accessible from the Windows "Control Panel"

Important: If the browser is running, you must restart it after you have made the changes.

You can profile applets started with appletviewer command by passing -J-Xrunyjpagent or -J-agentlib:yjpagent as a command line parameter. Read more in the Enabling profiling manually section.