Honestly, I don't think there's anything wrong with Gamebryo by itself.

First of all, engine binaries can be updated. Yes, Gamebryo is old. You know what else is really old? Source, and if you think Source 2 was built from the ground up without using any code from the original Source engine you'd be dead wrong. Both these engines have gone through numerous updates throughout the years.

Secondly, the Gamebryo engine seems to be absolutely marvelous for MMORPGs. Dark Age of Camelot, Rift, Warhammer Age of Reckoning... me and my guild have fought in PvP fights in these games that would bring the WoW engine to it's knees, yet those games handled them very well. I've seen what happens when comparable fights happen in WoW, it's an ugly sight. Frames would turn into slideshows, and the slideshow would turn into crashes.

Third off, the Creation Engine is the Creation Engine. It has bits and pieces of Gamebryo (most notably the way it's file library is processed, more on that later), but so much of the engine has been rebuilt that you just can't call it that anymore.

Forth point. The way Gamebryo (and later Creation) organizes files was perfect for the Elder Scroll series style of modding. Modular modding is virtually unheard of outside of Bethesda's games for this very reason. This engine is the very reason you can install multiple mods (up to 255 plugins) and still have a working game.

Fifth point! There is nothing wrong with Gamebryo's memory allocation at it's core as far as I know. It simply appears to be an unforeseen issue with the limits of Skyrim's exe, which can only hold 3 gigs of memory before it crashes. What I DO know is that Skyrim modders actually managed to circumvent the memory allocation issue by running additional exes and holding memory there in recent years... which proves the engine can handle the memory issue.

You mention the physics getting weird in relation to refresh rate. Do you not realize that this is an issue with Havok, a standalone physics engine and not with Gamebryo? Gamebryo doesn't have a built in physics engine, buddy. Havok physics have always gotten weird with abnormally high frame rates.

I'm sorry I'm writing a novel here, but there were so many things wrong with what you've been saying about the engine that I just had to interject. Like you said... you don't know much about engines, right?

Bethesda gets a lot of shit for bugs and problems with their games... but don't blame it on the engine. As someone who is very familiar with the engine and the core files of Bethesda's games, I can tell you with confidence that the problem is with how sloppy their game designers are.