I also saw the 1*1 tilemap solution.
If you simply want to create a hole in a picture with no more effects like your tank game, the Canvas plugin itself can do that very well, just paste any sprite on your canvas with a "Destination out" blend effect.
It's very efficient and I think even with big holes. But maybe you've already tried this ?
My project is slower more complicated because I really want to count each pixel in order to have a proportional number of particles.
I need to use a faster algorith to count the pixels inside the explosion radius, and I'd also like to find a faster way to update my array, I don't know if it is possible.
BTW, I've also added an increasing/decreasing radius option with the mousewheel as you did, so you can see the actual (bad) performances with more pixels to remove :
Also, my canvas is quite small. I bet the performances decreases a lot with a bigger canvas.
Edit : well, they don't. Takes some time to put all the pixels into the array, thought.