In the early days of 2018, the engineering team at the mobile services company Branch noticed slowdowns and errors with its Amazon Web Services cloud servers. An unexpected round of AWS server reboots in December had already struck Ian Chan, Branch's director of engineering, as odd. But the server slowdowns a few weeks later presented a more pressing concern.

"We had six engineers crammed in a small war room all staring at charts, deploy logs, revision histories, and latency graphs looking for the cause," Chan says. "We spent a few days eliminating possibilities one after another, but were unable to find a root cause. We were seemingly chasing a non-existent bug in our system."

The team kept Branch's services operational by reworking some of their architecture, and purchasing more server capacity from AWS to stabilize the workloads. "At some point someone floated the hypothesis that it was an underlying performance issue due to the Spectre and Meltdown patches being applied by AWS," Chan says. "The mystery reboots from just a few weeks earlier suddenly made sense."

Branch's struggles turn out not to be unique. Last week's public revelation that most mainstream computing processors could be manipulated to leak data between programs led to a frenzy of patches and confusion. Even before Meltdown and Spectre were officially revealed, there had been hints that the fix could significantly degrade performance. And while system administrators, internet infrastructure providers, and cybersecurity managers now largely agree they've dodged the early worst-case scenarios, they've taken a tangible toll.

Taking Your Medicine

The Meltdown and Spectre vulnerabilities exist because for years chipmakers have taken steps to prioritize performance and speed that, as a side effect, turned out to impact security. By reining in some of these data fast tracks, the fixes slow down certain types of operations, particularly for programs that require a lot of requests to the kernel, an operating system's most fundamental and secretive inner sanctum.

'I remember first looking at it and thinking 'oh, shit,'.' John Michener, Casaba Security

Early testing and benchmarking of the Meltdown and Spectre fixes indicated that their impact could be severe. Even just the complexity of applying and managing the patches—particularly for Spectre, which is more a class of vulnerability than a specific bug—has created a real strain on the industry. Lots of vulnerabilities require large-scale patches. But Meltdown and Spectre are unique in that they involve overhauls of both standard operating system software, and more rare updates to the firmware and microcode that coordinate and control hardware.

"I remember first looking at it and thinking 'oh, shit,'" says John Michener, the chief scientist at the security consulting firm Casaba Security, which has helped retail vendors with Meltdown and Spectre remediation. "We'll see Spectre-related bugs for the next five years. But in general this type of thing has happened before. We may see a marginal impact and take a bit of a hit, but the newer processors don't have a huge loss. Older processors have more of an impact."

Dampening the potentially crippling performance issues has required a massive, coordinated effort behind the scenes. Some companies, including the open source enterprise IT services group Red Hat, had advanced notice about Meltdown and Spectre before the public disclosure, getting a head start on the patching process.

"There certainly is a performance impact, but what we had to do is kind of use the big hammer initially to mitigate, and then we can go back to iterate and refine," says Red Hat chief ARM architect Jon Masters. "There's potential for improving these fixes."

Deeper Impact

That's not to say everything's fine and rosy. While Intel and other processor manufacturers initially worked to downplay potential performance problems from the patches, the industry immediately started feeling ripple effects.

In a Tuesday update, for example, Microsoft said that consumer devices with processors from 2015 or earlier running Windows 7, 8, and 10 would be more likely to exhibit slowdowns. The company added that, "Windows Server on any silicon, especially in any IO-intensive application, shows a more significant performance impact when you enable the mitigations."