Microsoft has released a PowerShell module on PSGallery that can test if you are mitigating the issues that Meltdown and Spectre are using.
Simply run the following command in an elevated PowerShell window:
Then use the following command to verify mitigations:
This was the result om my laptop (Lenovo X1 Yoga) before patching it:
Then I installed this patch (via regular Windows Update):
After installing the patch and rebooting, it looked much better:
Note that some of my older hardware only managed to mitigate some of them, and some mitigations are sometimes not turned on by default, due to some dependencies.