runouw.com

Personally, I think The Secret Aquarium wasn't a good choice for a remake: the original level can be completed in about a minute if you know what you're doing.

This level, however, cannot. This is because this level is much larger than The Secret Aquarium. It measures 100x100.
I have never made a level that large, and this level can show why it's a bad idea: namely, there's very little in the way.

While there was nothing much in The Secret Aquarium, it being a small room helped because it wasn't meant to be a big level.
It was meant to be a little snack before the meal, figuratively. This level is simply too big for the idea. You need to shrink it.

I give this 1/5 because there's nothing really there. The coins are about as well hidden as in the original (read: not at all hidden).
What you did add were a couple obstacles around the red coins, which bumps it up a little (1.5/5) but there's still way too much nothing.

I suggest you shrink this level to 30x30, or remake another level. The level you were remaking was nowhere near that large.
Of course it's only laggy because it's so big.

I'd like to mention here that the original level had four stained windows, while this does not. However, that's only minor.

In short, you're getting 1/5 because there's no fun to be had here. There's too much room and not enough obstacles.

The lag actually comes less from the size but from the fish in the middle and the blocks with many coins. But of course, in such a small transition a smaller amount of "lagerogene" stuff (a word that I always wanted to use :>) suffices already to let the frames drop beneath 10 fps temporarily.

More than that, the large distances to travel were generally annoying, as noted above.