No, cpu wise there should not really be an overhead, as it just uses docker or podman to run the application in question. the only bottleneck i see could be host filesystems that are not supported by docker/podman and therefore could lead to slow file access in the container.
It depends a bit on the filesystem that you are choosing for proxmox however. Afaik there are still problems with zfs as the host filesystem and docker in an lxc. the general recommendation is to use an extra virtual disk that is ext4 formatted for
/var/lib/docker
.