Abnormal RAM usage with Vulkan when compared to OpenGL

[Kizoky]

I have noticed something weird with my mod when playing with OpenGL and Vulkan
in Vulkan GZDoom uses 2.5-3GB of RAM in my levels (they are called world1 -> world8)

However with OpenGL the RAM usage is much more normal and uses less (700-900mb), in LZDoom too

I have tried providing an example mod but I have no idea what causes the high RAM usage as I thought at first it was my models that have high polygon amount in MD3 format, but with that example mod the RAM usage is 300mb both in OpenGL and Vulkan

Steps to reproduce: (and sorry for the big download size, but I couldn't find out what was causing the high RAM usage)
1. Download the mod from this mirror (1.5GB): https://drive.google.com/file/d/1O63q85 ... sp=sharing
2. Play with the mod with either Vulkan or OpenGL to compare
3. in console enter a map called world1 or world2
4. Look around and move a bit
5. Check in Task Manager the RAM usage

(world1 map)

OpenGL:


Vulkan:

[Graf Zahl]

It's a known issue. Due to how Vulkan uploads textures the uploader was written to retain the texture copy in system memory. Unfortunately with the current Vulkan code there's not much hope this can be fixed.