Okay. Let me clarify a couple of things here. First of all, Meltdown and Spectre ARE real, so this isn't some doomsday viral post. That said, it's mostly a problem for virtualisation and enterprise networks (which is my job, so it's a legitimate concern for me).
A Linux kernel update has already been released to resolve the issue. The performance drop is ESTIMATED to be between 5%-29% (it's not concrete yet). Microsoft are aiming to put out an update to patch it on January 9th.
Even if a performance hit arises due to the patch, they do have a goal to make it minimal, if not, nonexistent. So keep in mind that the January 9th patch will be for "early adopters".
It is not known if this affects AMD yet, and they're looking into it. They'll post on their website when they have found out if it affects them or not.
This does, however, affect AMD ARM processors, and Google have already stated it affects Android. They're working on an Android update to resolve the issue.
SharkEdit™: It's bad, but we're working on it. Looks like you can keep calm and Intel on, just make sure that you keep your systems updated. See: https://security.googleblog.com/2018/01/more-details-about-mitigations-for-cpu_4.html