Detecting slow Protractor tests

The Story

We have a big end-to-end test codebase written in Protractor/WebDriverJS.

We are using jasmine-spec-reporter for the command-line test reports. It reports test execution time for every test spec:

About screen when logged in
    ✓ should show the license text after refresh (51 secs)

  About modal
    ✓ should show the correct title (0.396 sec)
    ✓ should display component versions in a correct format (0.782 sec)

...

The Problem

The problem is - we have multiple tests that are much slower than the others - performance is becoming critical when these kind of tests are used for "smoke" tests against production instances.

The Question

Is there an effective (preferably automated) way to identify the bottlenecks - the reasons why these tests are slow?

Ideally, it would be very convenient to see line-by-line breakdown reporting how long each line execution took. I am currently thinking of tweaking Protractor's "Control Flow" to log execution time of every single "command" coming through..