The SVGs in question were 6kB and 568kB in size, respectively.
At 25% size (around 256x256px) the PNGs were 13kB and 30kB respectively.
At 100% size (around 1024x1024px) they were 60kB and 266kB respectively.
I scaled the complex image to 200% (2048x2048) just out of curiosity, and it became 841kB, roughly 28x the size of the smallest, which uses 1/64 as many pixels. It is interesting that the complex image seems to approach size growing with area at the high end of resolution. Of course, this is a sample of 2.