It needs to be accurate and fast, indeed. The code being old isn’t a problem unto itself, but rather the side effects of it.
It is fine for all intents and purposes today. But, there is some inherent difficulty associated with decisions brought years ago when some of the code was originally written, making portability quite a challenge.
I wasn’t making a comment on its age, mind you. I don’t necessarily think it’s that big of a problem and probably can be fixed easily. If anything, it has gotten way better thanks to the departure from the plugin system and various other optimizations over the years.