For a detailed discussion of this problem, including a suboptimal fix, see #17774 . The TL;DR is that since calling text change callbacks for every character of a large unified change is pointless, we should find a good way of inhibiting the callbacks while the change is going on. Some callbacks are very performance-intensive, some modify the document themselves, etc., so we want to call them as little as possible. I'm pretty sure that in the case of GMLPlayground, we should be able to achieve 2n runtime instead of the current n².