is that asset/ level streaming or texture streaming? texture streaming is common in vram level streaming is system ram and also this doesnt answer my earlier question that u keep changing goal posts about,....UE4 doesn't stutter only because of shader compilation, it also stutters from asset streaming. You can test this yourself, by running a game first, let it compile shaders on runtime. Then run the same level again, with the shaders already compiled, and you still get stutters, but now from asset streaming.
This is common knowledge for anyone that plays on PC.
And yes, PCs cache data in the vram. UE4 is an example of this.
Here is the command to set the percentage of the streaming cache into the vram, default is one GB: r.Streaming.PoolSize.VRAMPercentageClamp
Here is the command to set the streaming cache only to vram: r.Streaming.LimitPoolSizeToVRAM