500 Row Limit - What Counts?

Sorry to go off topic, but do all formulas in Google sheets cause a delay, or only ones like this Vlookup? I ask because I put a column into my Google sheet that’s simply a lowercase conversion formula, and ever since then my app takes five full seconds to load instead of the immediate load it had before. (I have a relation within Glide to this lowercase column too) I had made several changes at once in addition to this one before the delay occurred so I’ve been avoiding the nightmare of trying to track down the culprit! Are formulas a main suspect?