uncontrollable random spikes

Hello!

My problem is uncontrollable random spikes in the game (lasting about 0.5 sec). No matter what I do, it just happens sometimes on any iOS device (ipad mini retina/iphone). I connected the profiler, and I see, that at the moment of this spike - the peak in "CPU Usage" section appears, 1 frame peak. But everytime I investige the reasons of this 1 frame peak I see the different reasons:

1 time I saw the Canvas.BuildBatch -> Canvas.GenerateBatchedMesh used 96% of total time (290 ms), 1 time I saw Overhead used 99% of total time (1200ms), 1 time I saw Graphics.PresentAndSync -> Device.Present used 98% of total time (300+ms)

I can't figure out what is going on, and I need your help. Thank you.