Varf and speed of calculations

Dear freefem community,

For the sake of simplicity and generalization in using many freefem codes, I wonder if it is critical or not to write only one freefem varf with many parameters that could be zero rather than write many different codes.

For example,
varf Myvarf(u,v) = int3d(S(v)’ CS(u)) + tau1 * int3d(phi(u,v)) + tau2 * int3d (psi(u,v)) + …
Can I use only this varf even if tau1 = 0 and tau2 = 0 ? Or is it preferable for speed of calculations to write (here) 4 different codes (without tau1,tau2 or with tau1 or with tau2 or with tau1&tau2) ?

For my application, I write a thermopiezoelectric freefem code, but if I take into account the green-lindsay theory or Lord-Schulman, many parameters could appear.

Thanks in advance,