BoltWire comes with a built in stopwatch feature you can use to test various configurations, plugins, etc, to benchmark performance. To use it, put the following in index.php before calling the engine.
$BOLTstopWatch = true;
It tracks various points in the site processing. You can track other points by inserting the following into the code at various points in the code. You could, for example, insert this line at the start and finish of a function, to measure how long that function took.
BOLTstopWatch('Some unique message');
To make it visible, you need to also add before calling the engine...
If you are not already using that.
Remember, this output is visible to all users (not just admins), though perhaps that could be made to configurable somehow. Generally, it is used offline for development purposes.