How much should I beat choux pastry for optimal rising?
You have gotten a fundamental principle of the choux pastry wrong. 

The rising and airiness is not caused by beating air bubbles into the batter, unlike with sponge cake and similar, but by trapping steam in the well formed network of gluten and egg in the batter.

The cooking step is not meant to just have the flour-water-fat mix come together, but to have the starch in the flour starting to gelatinize, i.e. develop the properties that bind pudding or roux. So you have to keep cooking and stirring the lump of batter until a white film forms on the bottom of your pot (assuming you are using stainless steel or similar, not a non-stick coated one). Without that, your batter won't be able to trap the steam created during baking, which forms those large holes characteristic of choux pastry.

There is no need to stir vigorously when adding the eggs, add them one at a time and stir only to incorporate them. Do not beat your batter, you would be doing more harm than good.

Apart from that, follow the usual advice and don't open the oven door during baking and you should be fine. You can add some extra steam by splashing some water into the oven, but that's optional.