Certainly many sites with tons of tracking are worse than most internal sites. You will not get a disagreement from me on that.
I can't really cite examples, as I'm not at the old job. But silly things like our "news" homepage was getting so that it lazy loaded all of the news. HR things would load in parts, too. And issue tracking seemed to constantly be a mess.
The tool my team controlled had bloated to excessive points. Some of that was almost certainly my fault. I had designed a somewhat granular backend. That said, I remember things were certainly faster before we had a ton of redux based code to do things.
There was this really horrific one I did experience, come to find out the entire company is relying on this angular app that connects to an ancient mac mini that IT is responsible for but mostly forgot about. Wasn't a large company, but they weren't stalling in growth!