How to read measurment of FPS in Mac 'Instruments' (Core Animation) while debuggin Mobile Safari on iPad?

I'm using Yosemite and OSX Xcode 'Instruments' (Core Animation) to measure FPS in my iPadMini Mobile Safari browser app. However, the reading I get looks contrary to the reading you get while using 'timeline' and Chrome Dev Tools. Please see the image from 'Inststruments':

and Dev Tools Timeline:

When you don't perform any action (fire no events) in Dev Tools you get 60fps+ (see the image above) and that what I would expect. However, in Mac 'Instruments' - Core Animation - in the same state you have ~7fps and FPS rate rises as soon as you start fiddling with the application (fire some events).

I'm confused and would appreciate any help.