Thanks for taking the time and sharing your thoughts. I do currently have a progress bar during the loading and the game actually "only" loads about 65MB before the game starts (the rest, textures, music, larger file for other stages, get loaded only when the player reaches these sections of the game)... Sorry for the confusing wording. I'll change it.
And yeah, you're right about the shadows. The bubbles already cast a faint ring shadow on the ground, but the question might be whether it's visible enough / effective enough to read / solve the potential issue. If you try the game, tell me if you noticed it.