Things about DXVK you must acknowledge:

• DXVK improves performance in mainly draw call (CPU) bound scenarios (e.g. draw distance), and usually doesn't help much in GPU bound ones (e.g. resolution)
  
  • It is possible that DXVK won't change anything for you, or even make things worse
    
  
  
• DXVK 2.0 and higher require:
  • A Vulkan 1.3 compatible driver
  • A VK_EXT_robustness2 driver extension
    
  
  

Generally almost all modern (2015+) GPUs support them, but if you'd like to sanity check yours, use GPU-Z, and go to the Advanced tab -> Vulkan section.
Those functionalities are a part of your GPU driver, so make sure you have the latest available version.
Keep in mind that even with those conditions met, DXVK 2.0+ may not work correctly for you, due to its Linux-based nature.

DXVK's GPU compatibility varies between manufacturers

• Nvidia GPU laptops must use the DXGI interop.
  Using it on desktops is not required, but highly recommended for the most optimal experience
  
  
• AMD GPUs must use the DXGI interop, otherwise they will suffer from severe performance issues or fail to launch the game.
  Shader issues are more common on Windows compared to other GPUs (situation is completely reversed on Linux).
  
  
• Intel GPUs from 6th Gen and newer can work provided you have newest drivers installed.
  DXVK is broken past the 1.10.1 version.
  Don't expect a big performance difference, if any, since the game will still be mostly GPU bound.
  Arc GPUs should work fine, but are untested.

Fallout New Vegas has some known shader issues or quirks. They are not guaranteed to happen (getting rarer with DXVK updates), but they can occur:

• Transparency multisampling uses dithering - (DXVK handles alpha to coverage differently than drivers)
• Blood decals can suffer from color overflow and turn white - uncommon, most reports come from AMD GPUs, but issue can appear on Nvidia
  

Due to DXVK's nature it relies on shader cache, which is compiled during the first use of that shader.
Because of that you can experience increased short stutter at the beginning of your playthrough.
This is completely normal and will not reoccur after compilation has finished.

DXVK-GPLAsync patch by Ph42oN and Sporif alleviates this problem thanks to making the compilation asynchronous.

DXVK 2.0 and newer precompile shaders on launch, although at the time of writing, on Windows, this feature is Nvidia only. Ph42oN's async patch uses both methods, so it's safe to use on all GPU manufacturers.

HDR Mod

HDR-Mod is a DXVK mod made by Lilium (aka EndlesslyFlowering) and Wall_SoGB with the intention of adding HDR functionality to D3D9 games. Effectively it does 2 major things:

• Displays the game at bit depth higher than 8.
• Upgrades render targets to 16 bits.
  

This allows for HDR output and eliminates color banding from the game.
DXVK doesn't perform any HDR tone mapping, so you need to use Pumbo's ReShade AutoHDR or Special K (Nvidia only) for that.

Known quirks and issues

• Any images produced by the game that were meant to be in 8 bit (screenshots, save images) are distorted due to lack of color conversion.
  This is purely visual and doesn't affect gameplay.
  HDR Save Image Patch and New Vegas Reloaded fix save images.
  For screenshots it's recommended to use Game Bar, Steam (Beta) or your tone mapping utility.