I would give a fairly large amount of money for people to stop fixating on page speed at the expense of things that actually matter. Page speed is one of those things that Google used to get web designers and SEOs to save Google money by reducing its bandwidth costs wrapped in an 'it's for the people' blanket. Your only real goal with page speed should be to be as fast, or faster, than your competitors. That's it. Anything else is gravy. And if you are choosing between page speed and something important like a tracking pixel, you are already on the wrong side of the equation because, by that theory, you should remove Google Analytics since it can, and does, slow your site down as much as anything else. As @
mesocratic said, you could use tag manager, but, in the end, the pixel is far more important than speed.
☰