Does "if" help with procedures triggered globally?

Topic title basically explains the question. I found myself running some global triggers, but I know that they are main source of lag and decreased performance due to being run constantly. Not that I need to know that *immediately*, but for longer run it can be really helpful.

So the question I have is: does "if" reduces the lag, so global trigger is used in less-heavy way? (you don't run procedure blocks until it's true)
And is there any other way to reduce global trigger heaviness?