the games graphics are like half-life 1 it should not lag at all thats so weird
Gpu is not the only thing that runs your games smooth, VOTV is kinda CPU intense too and its made on Unreal Engine 4, maybe you see lo-fi textures and think the graphic is "HalfLife level" but it's not, it has a lot of advanced lighting/shadows and a lot of physics calculation too. Being in alpha stage, consider that the whole game is just poorly optimized for obvious reason.
It's open world and features real time lighting. Many decals. Many more particles. And complex physics systems. Even though the textures use point sampling I am sure there are still complex shaders going on under the hood. That being said performance is a work in progress and is expected to improve in future versions. The base is the most complex and dense area on the map so it's expected that the performance would be the lowest there. It is important to understand the bottlenecks of your setup so you know where to reduce settings and where to increase them. So for example I am on a 4k monitor but I have a slow GPU so I reduce the resolution scale to 50% and turn on TAA, but because the GPU has 12GB of memory I increase the texture resolution and heap size to 7gb.
The only way for the developer to increase the fps at the base would be to unload the rest of the world while you are at it. Like when you are at Whiterun in Skyrim.
Optimization is usually one of the last steps in a game's development cycle. I'd expect it to be improved a little before release.