Some people really are seeing those slowdowns though, it all depends on your workload. If you’re one of the people slowed down by 50%, i imagine the fact that you’re an outlier is cold comfort.
As mentioned in the article, there are 3 different (identified) vulns, each with its own set of patches, and sometimes multiples different ways to patch. Each of those patch will have its own impact, and work is currently in progress to find new ways to patch that will have a lower impact on performance.
Also, this means we will need to be used to patch, as new vulns of this category will definitely be found, and new changes to kernels/cpu/compilers will be designed and will need to be applied.