A massive performance hit is the most noticeable side-effect of the Spectre fixes that Microsoft has had to release this year.
Recent Meltdown Stories
Intel's upcoming processors will come with silicon level fixes for Meltdown and Spectre with updated processor design.
More Windows systems start getting update Intel firmware and fixes for Meltdown and Spectre.
Microsoft is helping Intel rollout firmware updates for Meltdown and Spectre, starting with Skylake processors.
Intel is releasing fixed patches for a subset of Skylake systems as the company continues to struggle with reliably patching products affected by Meltdown and Spectre.
Microsoft outlines performance impacts caused by patches for Metldown and Spectre on Windows machines. TL;DR: PCs with older CPUs and Windows are being hit the hardest.
Microsoft releases updates to the Surface UEFI to protect customers against the new CPU vulnerabilities as it continues to closely monitor the situation.