From: metro Chicago, Illinois, USA
It really boils down to – as we said, and Intel pointed out – your workload. If you just play games on your PC, you will not see a slowdown because the software rarely jumps to the kernel during gameplay. Your game will be mostly talking to the graphics processor.
If all you do is browse Twitter, write emails, and type away in a word processor, you probably won't notice any difference. If you do a lot of in-memory number crunching, you won't see much of an impact because again the kernel isn't getting in the way. If you have PCID support enabled on your hardware and in your kernel, any performance hit should be minimized.
If you hammer the disk, the network, or use software that makes lots of system calls in and out of the kernel, and you're lacking working PCID support, you will see a performance hit. And it's a good idea to warn you, right?
It's a given for this particular issue that any slowdown is dependent upon the kind of work the affected system is being asked to do. Gamers will maintain their frame rates, but that's not what this is about. It's about enterprise workloads and data centers. With reports of SQL database slowdowns of up to 20 or so per cent, it seems premature to say the impact should not be significant. If a company's AWS, Microsoft Azure, or Google Cloud bill ends up being, say, three, five or eight per cent higher as a consequence of prolonged compute times, that's significant.