Yes, you are right iteration control affects electronic convergence.

While increasing mesh and K point do help a system converge but it makes it converge slower.

A tip for fast convergence would be:

1. If you are suppose converging an unpolarized system, try first with low k point while keeping mesh cutoff higher or normal is what to be kept. After your system is converged at low K point increase K point to what u want. This can help achieve quicker optimization

2. If you are stuck with polarized optimization, then best is to perform unpolarized optimization first then use converged file to perform polarized optimization. This surely has worked in my case & is well reported method.

3. Another way is to increase your cores or nodes to achieve quicker optimization.

4. If still you are not getting quick optimization, perform a small atomic rattling for your structure in builder and perform any of the above steps. This should help too.

5. If still you are not getting quick optimization, then contact synopsys at solvnet.