Hey, thanks for trying the demo and yes, a new demo should be coming up very soon with a lot of changes. :)
That pedestal room issue has been fixed assuming you mean the room which is half submerged in water with spikes at the bottom.
There will always be some scaling artifacts since the game is actually rendered at 200% scale, this is done to be able to render the text as small as it is, it would be double the size if the game was rendered at 100%.
That being said, I'm looking into good ways of rendering the text separately to allow 100% game scale rendering, still have not found a good way though.
"Fit to Screen" will have black bars on any widescreen monitor as the game is not made for widescreen, and this is not possible to change either.
It does not use Integer Scaling and actually does Aspect Ratio Scaling unless Aspect Ratio Scaling means something else to you.
It should not have black bars on all sides of the screen though, just the sides or the top/bottom, a screenshot of this would be nice unless I'm misunderstanding here.
Technically the only reason V-Sync would make the game run at 30FPS would be if your monitor is running at 30Hz, unless something is broken.
Not sure about the 8-10FPS thing though, but one thing you could do regarding V-Sync is to turn on "Alternate Sync" which may or may not fix the issue.
Thanks for the feedback :)
If you're interested in providing more direct feedback or maybe knowing more about the game, feel free to join my Discord server, there's a link to it on this game page.
If not, then that's fine as well, I just respond faster on Discord. (+ there's a benefit or two for being there)