The request animation frame time is where the c2 runtime is running through your events once to tell the graphics card what to draw to give to the browser for the next frame of your game. If the whole process takes more than 16 ms then you will have jank.
There are 3 main things that can cause a super long animation frame request.
An issue in your events at this time like an loop issue or a huge parsing sorting array issue or performing a calc on 100 objects at once etc , ie something that will hang up the CPU.
An event that is producing a lot of sprites all at once, big sprites, or lots of sprites with effects all at once like in a for loop. Basically something that will hang up the GPU.
Something running in the browser on a different tab or another program running on the pc that is accessing resources or network every couple of seconds eg YouTube streaming video or your
face book or email update. even Spotify playing in background will cause
regular janking as the pc or browser prioritises this operation over the animation frame request.
If you are seeing exactly the same timing on different devices then it sounds like an events or graphics thing. Maybe disable some of animation s you think and test performance again.