Hard to say what would cause it to be low FPS consistently on a phone, but it looks like your current lag spikes are in line with garbage collection. Would you share any scripts that use an update loop? Make sure and use code tags if you do.
If you enable deep profiling at the top of the profilier and select one of the frames with the largest lag spikes, you can look at the frame time breakdown at the bottom of the window for what is taking the longest.