The FPS is exactly 60 here, are you sure VSync is not enabled?
Well, the FPS counter isn't visible, but what I can see is:
* You're moving at ludicrous speed that is unlikely to happen during gameplay.
* Your Cell Preloading feature is completely broken because you've set in your CFG file 'prediction time = 250' (normal value is 1). That's probably why you see loading screens. Sorry, the engine can't predict your position 4 minutes in the future.
* The second video is choppy, as expected with a greater cell load distance. Cell load distance is mostly to be used for scenic screenshots, it's not meant to be optimized for real time gameplay. An optimized version of rendering distant cells would be possible in the future, I've outlined this here
I think most of your problems boil down to changing settings that you don't understand. As the documentation states, you need to be careful with those. Try to revert to a default copy and then change one setting at a time, making sure you're still happy after each change.
The entire time Memory never goes above 3.5GB of RAM
What do you expect the extra memory should be used for? Memory is for storage, you can't use it for computations or magically increasing your FPS.
To make more use of memory, you can:
* install high-res texture / mesh replacers,
* use a high resolution display & turn up anti-aliasing,
* increase cell-preloading settings,
* know that having memory left over is perfectly normal, and leads to benefits in the form of files being cached by your OS.
never uses more than 17% of my 1080 GPU
I'm not sure where that figure is from, but on the first video the orange bar is mostly full, your GPU appears to be used about 80% in some scenes.
But, you've set 'framerate limit = 100', so in the cases where the FPS could have gone higher than that, of course the GPU usage will plummet.
During loading screens or stutters caused by not using Cell Preloading, of course the GPU will not be used, either.
It's not. The game uses 4 threads by default. You can use more if you want, go increase 'preload num threads = 1' (more than 3 is probably not useful, though)
Even with no extra engine optimization at all, I get the feeling we'd see a smoothness in gameplay and cell transitions comparable to Skyrim or better just by fixing the game assets. However, since nobody's talked seriously about undertaking such a project, I'm holding out hope we'll still see some performance improvements yet
Probably not from me, or at least I can't think of any ATM; apart from Vulkan, which would be a very big undertaking. There was some talk of a vulkan-based successor to OpenSceneGraph, but not much seems to have happened on that front yet.
the engine is 32-bit
This statement doesn't make sense in the context of an open source engine. Your computer is 32 bit or it isn't. The engine can be compiled as a 32 or 64 bit binary as you wish. If you look on our download page, we do offer both.