Really? I work across multiple vscode projects (locally), some use dev-containers and others don't. I have never noticed any difference in experience across the two.
I have also used them remotely (ssh and using tailscale) and noticed a little lag, but nothing really distracting.
No, on Windows it is very quick too. On WSL2 compiling Rust programs are almost as fast as Linux on bare metal. However the files need to live inside the Linux filesystem. Sharing with Windows drives actually compiles slower than native Windows.
If you are building natively, yes. However the original comment is about Dev Containers which runs under WSL2.
If you open a native Windows folder in VSCode and activate the Dev Container, it will use the special drvfs mounts that communicate via Plan9 to host Windows OS to access native Windows files from the Docker distro. Since it is a network layer accross two kernels, it is slow as hell.
First of all it supports containers natively, Windows own ones, and Linux on WSL.
Secondly, because Microsoft did not want to invent their own thing, the OS APIs are exposed the same way as Docker daemon would expect them.
Finally, with the goal to improving Kubernetes support and the ongoing changes for container runtimes in the industry, nowadays it exposes several touch points.
I have also used them remotely (ssh and using tailscale) and noticed a little lag, but nothing really distracting.