(Some of these things have already been reported, please bear with me, I just wanted to group things together. Some entries will use more appropriate technical terms to describe the issue.)

• Groups of people noticeably slow down the rendering. Most likely due to the facial animation/expression software. No workaround available for me at least. That so-called dx9 dll "fix" causes more problems than it pertains to solve.
  
• Clipping/sorting with the world environment: sometimes you, as player character, can get into a sorting match with the world environment and lose. This effectively causes you to sink halfway into some big rocks. This in turn seems to cause a looping jump/fall animation from which you cannot save yourself by fast travelling. No amount of crouching, jumping, or wiggling seems to get you unstuck. Saving and reloading does not reposition you in the world, so you stay stuck. Only workaround so far is to reload a previous save game. Since I didn't have explosives with me I haven't been able to test this to get myself unstuck.
  
• The same clipping/sorting happens with items and certain creatures in the world environment, most notable example: True Police Stories magazine inside the police car at that gas station with toxic waste dump. Good luck trying to pick it up without it dropping through the car floor.
  
• Some fights seem to trigger a blue colour fullscreen texture recolouring, as if you are using cateye. There are two workarounds I found so far: reload a previous save game (but this might cause the problem to reappear when you fight the same battle again). Another one is taking cateye, if you have it, after cateye works out it resets the texture colouring to the original. I have had only one different case. This was near Callville Bay, with the Cazadors in the boot repair building. During the fight the textures recoloured, but in a sandy/khaki shade. Not sure if the two are related.
  
• Caravan cards cause a lot of crashes with barter menus. Also, when you buy them they stay as separate entries in your inventory (this might be the same kind of bug as with ammo boxes, powder jars and the likes). You can store the cards in a safe/trunk/other container and the crashes stop. If you take cards from a container back into your inventory again they will be absorbed into your caravan deck and do not appear as separate items in your inventory anymore.
  
• Caravan deck adding/removing cards is just plain broken.
  
• Weathered 10mm pistol with mods causes visual problems (red/white texture) due to missing models. Workaround: don't use mods on it or install the workaround esm @ http://newvegasnexus.com/downloads/file.php?id=34794
  
• ED-E getting stuck against so many ceilings it becomes annoying. After a few seconds apparently some unstuck routine kicks in, which tends to free him. But you are constantly double checking to see if you have all your companions with you.
  
• Once a weapon you give to a companion has no ammo anymore, the companion keeps on trying to reload said weapon without switching back to the original weapon or next best one. Workaround: move said weapon back into your own inventory.
  
• The doorway into the monorail seems to sometimes be like an invisible wall.
  
• Jason Bright's speech stops after 1 or 2 sentences. This seemed to happen when I used my Pipboy during his speech. Second time I didn't cause any such interruptions and it continued as it should.
  
• The Helios One tower showed a consistent enemy inside while walking around the structure (ED-E in team).

I will add to the list as I encounter/remember things.