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What is the current status of this? The last time I heard, the OS fixes would impact CPU performance by 30%. Is this still the case? Will new iterations of Intel CPUs be immune to this, or is this an ongoing issue going forward because it's inherent with the architecture?

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Disclaimer: I work on Linux at Intel.

Future hardware will be mitigated against side-channel issues. There's a nice table showing how things are mitigated on future processors here:

https://www.tomshardware.com/news/intel-cascade-lake-details...

But, not everything is mitigated in the silicon or microcode. The mitigation for Spectre / Variant 1 / Bounds Check Bypass, for instance, will continue to be in software.

Based on my own experience with things and seeing other benchmarks, it looks like there's some synthetic benchmarks and very specific loads that will see up to 30% losses, but most things are really around 10-15% if they've got any significant losses at all. That's still a big impact but not nearly as "sky is falling" as it seemed like it might be. No idea how this'll be going forward with hardware changes since those haven't happened yet, and even when they do, how will we benchmark them properly?

Meanwhile, on HN frontpage: https://news.ycombinator.com/item?id=17876476

Everything I've read has said real workload differences can be as little as 3% or as much as 30%, but mostly somewhere in between (closer to the 3% side). Depends on what you're doing I guess.

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