Your next OS X update will reduce CPU performance by up to 40% | Hacker News Reader

Your next OS X update will reduce CPU performance by up to 40%

support.apple.com

12 pointsstanislavb7 comments

The title used here (“Your next OS X update will reduce CPU performance by up to 40%”) is an inaccurate summary of the support article.

Per the article, the update won’t affect CPU performance. It will apply Apple’s recommended mitigations for the recent batch of vulnerabilities for most workloads. But for users with higher risk workloads or who are planning to execute untrusted code, they’re adding a configuration option which would enable more stringent mitigation’s. Those mitigations have the 40% perf hit.

> But for users with higher risk workloads or who are planning to execute untrusted code, they’re adding a configuration option which would enable more stringent mitigation’s. Those mitigations have the 40% perf hit.

Execute untrusted code - so that would be anyone using a web browser?

The article mentions that the update includes mitigations in Safari, with no performance cost. Other browsers will have to do their own thing, of course.

Headline is slightly misleading here. The 40% figure refers to "full mitigation" which has to be activated via a terminal command. The default is for the update to apply a partial mitigation that protects Safari users from exploitation via JavaScript without degrading performance.

If Apple are considering moving to their own CPUs, I can only imagine mitigations like this are going to weigh heavily.

this is optional

The title is misleading at best. The quote per the article is :

"Although there are no known exploits affecting customers at the time of this writing, customers with computers at heightened risk or who run untrusted software on their Mac can optionally enable full mitigation to prevent harmful apps from exploiting these vulnerabilities. Full mitigation requires using the Terminal app to enable an additional CPU instruction and disable hyper-threading processing technology."

Not all Macs are affected by this patch and the reduce in performance will affect those with a hyper-threading CPU.

Reply on news.ycombinator.com