Excellent tutorial. However, lake(s) is/are very useful indeed. You can go over 5000 population/5000 gold with only one lake, robust agriculture (read: more remove cards), and continuously making room for new piers. Money itself is not relevant economic measure, amount and the basis of generation of remove cards IS, i.e. fields.
Unoptimised seaside surroundings of a pier glutter tiles will cause serious lag and untimely game crash long before 5K population.
From a dude, somewhat knowing what its all about. See below. ;)