Skyrim "Flying" Objects

Yes it is an FPS problem and yes, there is a fix - limiting your FPS. Several sites will direct you to information such as this which will corroborate that this is caused by the FPS. It's prevalent with any small objects and even small animals. The swimming is likely because someone's physics mesh has passed through something else and they think that they are swimming. Reducing FPS should resolve this issue as the objects and their physics meshes should be more in sync when their positions and collisions are calculated - there's probably more to it than that, but this covers the general idea of why your world seems to be exploding at the opening of a door.

The PC Gaming Wiki, "Skyrim" article states that "Disabling V-sync is HIGHLY UNRECOMMENDED. It introduces bugs with physics, time-scaling, graphics and controls", with this Bethesda forums post, "Do NOT disable vSync!" as its source:

The number one "fix" on this forum for Skyrim is to disable vSync through the "iPresentInterval = 0" tweak in the INI file. However over the last week or so it's come to many people's attention that disabling vSync this way causes all manner of bugs and glitches.

Notice that even if you force vSync through your GPU's control panel, Radeon Pro, DXD3Overrider etc, these bugs will still persist. The only way to stop them, unless noted otherwise, is to set iPresentInterval to 1.

Crazy Physics

Allowing your FPS to go over 60fps causes the physics engine to go a bit out of control. The slightest touch, even opening a door, can send pots and pans 10 foot away flying all over the place. Whilst this may seem funny, it can have disastrous consequences if a really important item flies so fast it gltches out of the playable area.

This can however be solved by limiting your FPS to 60.

Day and time out of sync

With iPresentInterval disabled, the time and day will gradually go out of sync. Shadows update correctly, shops close and open at the right time and the sun sets and rises correctly. However the physical day (for example Turdas) won't change until 5pm. This not only breaks immersion, but can also break some quests where the AI relies on the actual day changing.

NOTE: It has been confirmed that this will cause NPC schedules to go out of sync, and does break some quests.

This cannot be fixed with a FPS clamp, or by forcing vSync externally.

(there are also other issues with disabling Vsync mentioned in that forum post)

So, the solution is to enable Vsync internally:

• Go to %USERPROFILE%\My Documents\My Games\Skyrim\
• Open SkyrimPrefs.ini. Navigate to the [Display] section.
• Set the entry iPresentInterval=0 to iPresentInterval=1
• Save the file.