It becomes experimental science, you adjust various parameters and measure the result. Certainly to get performance but sometimes just to get APIs to work together.
This confuses the issue. The relevant question is --- as a programmer, would you consider yourself a "scientist" or an "engineer"?
In that context, we would not want to conflate the two, for example by trying to define why engineering ("adjust various parameters ... to get APIs to work together") is in fact science ("it becomes experimental science").
During the process of engineering, we of course employ the scientific method to accomplish our goals. But we would not want to consider engineering a purely scientific endeavor, in the way that, say, theoretical physics is a purely scientific endeavor.