The size of your pot matters. The larger the better. The amount of salt.
The best way to tell if you have enough salt is to taste your water - you want it to taste salty but not quite like the sea, more like your tears or sweat. Also, make sure to stir your water to fully dissolve the salt.
Raging Boil versus slow boil/simmer to cook your pasta.
While it is important to make sure your water has come to a full raging boil before you add your pasta, you do not want to cook it in a jacuzzi. After adding your pasta, reduce the heat to medium-high, transforming the boil into a slow rolling boil or heavy simmer.
Frozen versus Fresh Pasta.
Filled Pastas and Gnocchi should always be cooked directly from frozen. Other pastas can be defrosted prior to cooking but it is not necessary. All cook times work from frozen.