More details emerge on how much Meltdown and Spectre patches will slow down your PC

Meltdown and Spectre

We’re finally hearing more concrete information about the real-world performance impact of the big Meltdown and Spectre patches, with Microsoft making some claims about a more serious slowdown for those using older Intel chips, and/or operating systems previous to Windows 10.

Remember that Intel’s initial line – following the original stories about the patches potentially slowing down PCs by up to an eye-watering 30% – was that the average PC user should not experience any ‘significant’ (i.e. noticeable) slowdown.

According to Microsoft, those using Windows 10 along with Skylake or newer Intel processors experience “single-digit slowdowns”, meaning less than 10%. Generally speaking, Terry Myerson’s (executive VP, Windows and Devices Group) blog post (spotted by the Verge) notes that most of these users won’t notice any difference because “these percentages are reflected in milliseconds”.

This is roughly in line with Intel’s latest estimate of the slowdown effect of Meltdown and Spectre, in which (as CNET reports) the chip giant specifies a 6% (or less) performance impact – albeit in a modern system running one of its latest (8th-gen) CPUs along with an SSD. A relatively best-case scenario PC, in other words.

Intel noted: “Based on our most recent PC benchmarking, we continue to expect that the performance impact should not be significant for average computer users.” And the firm further observed that only specific tasks would really be weighed down, and that wouldn’t include basic computing tasks like checking your email or using a word processor.

Sticky situation

But, back to Microsoft’s estimations, and this is where things get slightly stickier – those running Windows 10 with older Intel processors (Haswell, which is 4th-gen, or older) will experience more significant slowdowns, and “some users will notice a decrease in system performance”.

Finally, Microsoft observes that in the case of those running older CPUs (Haswell or previous) along with an older OS – i.e. Windows 7 or Windows 8 – it expects “most users to notice a decrease in system performance”.

There’s nothing concrete here in terms of actual figures, obviously, but nonetheless this seems a worrying statement, and far from Intel’s assertion that the average user won’t notice anything significant happening to their PC’s performance levels.

Of course, the more cynical out there might suggest that Microsoft is taking the opportunity to push Windows 10 to the fore once again as a ‘must-upgrade’ proposition. But there doesn’t seem to be any doubt that the older operating systems don’t cope as well with the patches.

Microsoft explains: “Older versions of Windows have a larger performance impact because Windows 7 and Windows 8 have more user-kernel transitions because of legacy design decisions, such as all font rendering taking place in the kernel.”

The company says that its full benchmarking data will be published in the coming weeks, which is good to hear. It’s further worth noting that Microsoft observes that when it comes to the performance hit, it’s patching Spectre which is troublesome. Meltdown (which is specific to Intel chips) mitigation doesn’t have any real performance impact.

Spectre of side-effects

Meanwhile, regardless of any direct impact that the Meltdown and Spectre patches may have on your PC, you may also experience other side-effects when it comes to online services or games patching up their systems.

For example, as the Guardian reports, the developers of online game Fortnite said they experienced a 30% spike in CPU usage when applying patches for the bugs, which led to general instability of game sessions and indeed login failures for some gamers.

These sort of things will be temporary problems, of course, but clearly they’re still unwanted bits of fallout from this whole security flaw nightmare.

If you’re worried about these vulnerabilities, don’t forget that we have a full guide on how to protect against the Meltdown and Spectre bugs.

Darren is a freelancer writing news and features for TechRadar (and occasionally T3) across a broad range of computing topics including CPUs, GPUs, various other hardware, VPNs, antivirus and more. He has written about tech for the best part of three decades, and writes books in his spare time (his debut novel - 'I Know What You Did Last Supper' - was published by Hachette UK in 2013).