These are just some ways I fixed some bugs I encountered.

1. Flashing Lights(?)
I don't know if this is just me, but they seem to be artifacts.
Fix: Antialias set to 0. Also fixed some lag.

2. Verify File Integrity
Haven't tried it myself, but other game I had on Steam were fished by this.

3. Application Priority
Start NV.
Alt-Tab to Desktop when at main menu.
Start Task Manager > Processes.
Right-click on FalloutNV.exe > SetPrioity > High.

Possible Fixes That I can't seem to figure out how to get.

1. CFF Explorer
Using CFF Explorer with Fallout 3 allowed me to change the exe to be able to use >2gb of RAM. Upon my attempt to do this for NV, Steam would come up with a launch error. Kinda understandable.
ATTENTION: If you plan on modding the .exe, ALWAYS SAVE THE ORIGINAL EXE.

Hope these help you out.

Other Possible Fixes

4. Run as Administrator
Since you get errors/warnings when running Steam as Administrator, this could help.

Go to the FalloutNV directory, Example: C:\Program Files (x86)\Steam\steamapps\common\fallout new vegas
Right-Click on FalloutNV.exe > Properties > Compatibility
Check the last box (Run as Administrator)
Click Okay.
Do the same with FalloutNVLauncher.exe
Note: I don't know the in-depth workings of Run as Administrator, other than it allows the application more access. But if an application not run as administrator opens one that will run as Administrator, I can take a guess that the application opened by the other application will not work as well.

5. Auto-Save Problems
This happened to me. Even after many "should be" auto-saves, I still had the auto-save from when I first got out of the bed. I seem to have found a possible solution for if you get stuck with the same auto-save.
Delete current auto-save. Simple as that.