Technically yes, but it's not even vaguely in the same ballpark. If I've understood the devs talking about the optimization issues (I could be wrong! Just my limited understanding) the big performance hit is in the local feed. That means being on another instance takes a gigantic amount of the load off, even if you're still accessing the same community.
If lemmy.ml is down, so are all the communities hosted there. All communities not on lemmy.ml would still be up.