The recent released KB4056892 might cause trouble on some PCs according to some forum posts, here and here. In case you have trouble with this KB just uninstall it and wait for the next Patchday (9. January) next Tuesday. WinCentral was reporting that the Windows Mobile OS v15254.158 (KB4073117, KB4056891) in the meantime also got the KB (it’s rolling out right now), which might also could cause the same issue – some Windows phones using a SoC based on Cortex-A57 which are affected by Spectre and Meltdown vulnerabilities.
Especially server owner are suffering from the recent patch because it seems that there some performance problems with it, the problem is that there are too many Syscalls send which overall ends up with more network packages (send and receive). Linux developer Greg Kroah-Hartman has written down his findings., he is the Long-Term-Support-Kernel (LTS) maintainer btw, so I think he is able to give some good statements about the current status.
I suggest you simply wait, the Windows and Linux patches and current implementations are far away from finished and only a quick solution for a problem which isn’t fully analysed yet. It simply takes time to provide some quality patches for such big holes.
It’s still a question if bigger agencies were aware of these holes or not. The Washington Post writes that the NSA didn’t know about the flaw. Some people in California, Indiana and Oregon sue against Intel already with the argumentation that Intel sold them dangerous chips, they want a compensation for it – we will see how it ends in the upcoming months, the year just has begun and we will see plenty of more leaks I bet.