http://www.pcgamer.com/intel-reveals-0-25-percent-performance-impact-from-meltdown-and-spectre-patches/

Intel today revealed additional information regarding its ongoing testing of the Meltdown and Spectre firmware patches it has released. To date, the company says it has released firmware updates for 90 percent of processors made in the past five years. That says nothing about processors from before that time, but that's a different topic. Intel executive VP and GM for the Data Center Group also mentions the reboot issues previous discussed and says that it's "making progress toward identifying the root cause" and will be "providing beta microcode to vendors for validation by next week." But the bigger topic is the performance testing results for data centers.

While client systems are the least likely to be affected by the firmware and software updates, with generally negligible impacts to office tasks and even gaming, things become more complex when we enter the world of servers. Intel has so far only provided figures using industry standard benchmarks on dual-socket Xeon Platinum (Skylake) platforms, which are the latest generation server products. Given that even client workloads have shown more significant drops in performance on Broadwell and earlier architectures, the same will likely happen with Xeon parts.