Comma after To at the beginning of a sentence

I am just writing my master thesis and I am unsure whether to place a comma in sentences starting with "To".

Here are some examples:

• To be able to improve the performance[,] it is important to discover the performance issues first.
• To create consistent plans[,] there are two basic directions of planning: top-down or bottom-up.
• To acquire query plans[,] EXPLAIN PLAN statements have to be injected in the statements within the context of the application.

Is the beginning an introductory phrase?

I am German and therefore not familiar with English punctuation yet ...

To (also in order to, having the same meaning as in order that and so that) in each of those sentences is a subordinating conjunction, which is what begins a dependent clause. The comma is not necessary between the two clauses, but (as FumbleFingers says) it is preferred when it improves readability, which is usually when the first clause is rather long.

In your examples, I would prefer the comma.