Efficiently solving Poisson eqn repeatedly

[dokken]

There are several things in your code that is not efficient,
1.

@wvanharten

form = Form(RHS)

You do not need to recompile the form if f is in the same function space. You can simply create your form outside the loop and update f through interpolation.

@wvanharten

vector = create_vector(form)
    problem._b = vector
    problem._L = form

This should not be required, as the form should be constant in time, and the coefficients in f will be automatically updated during the solve stage.