At least for Meltdown there are CPU microcode updates out there that should mitigate it, which means the OS level mitigations can be rolled back. And I haven't

At least for Meltdown there are CPU microcode updates out there that should mitigate it, which means the OS level mitigations can be rolled back. And I haven't measured it yet, but I suspect the microcode mitigates are faster. Regarding Spectre, I think it's too early to tell.