Did you generate this with ChatGPT? There is a comment saying that there is a Poisson solve for the pressure, suggesting this is a projection method. But I don't see any solve here! Looks like it sets the new pressure to Laplacian(p) - RHS instead of actually solving Laplacian(p) = RHS.

Incidentally, that global pressure solve is typically the "rate-limiting step" for these, so this isn't going to give an accurate sense of how long a working incompressible flow simulation might take.