Halt on Canvas Snapshot?

I just found out that I could replicate one of my Paster-only tricks right in C2 by combining 'CanvasSnapshot' with the Sprite action 'Load image from URL' (which can take a dataURI as well) to paste a copy of my current screen to a sprite image.

In my case I'm using it to 'flatten' a number of layers together and apply a blur to it. By using this approach, I can smoothly 'fade-in' a blur effect even on my modest android device, which isn't possible when I apply blur to multiple layers. I can't blur the whole layout because I have an overlay that I want to stay unblurred.

The problem is, whenever I grab a canvas snapshot and past it to a sprite, the engine halts for a few frames (more than a few on android). I notice that we only have the option of grabbing the canvas as a png/jpeg. Is the on-the-fly (de)compression the reason behind this slowdown? Or is this just a demanding operation that takes a ton of CPU on its own?

You are not only compressing then decompressing but probably also hitting the disk which means IO latency... IO is far slower than in-memory operations.

I think I saw something like that hapenning, which is why I prefer to use the paster (as paster seems more adapted for real time interactions). I wonder why too however.