Only the PRoot method has some overhead, as it hijacks system calls with ptrace(). Linux namespaces or chroot shouldn't have noticable overhead.

> The Linux namespaces represents the default backend program for JuNest.

So no, you can think of it like docker without the sandboxing from the host. It just swaps out the host environment for the junest one similar to a chroot but doesn't require root (unless you're using the chroot method)