NextDNS fixes Safari ad-blocker CPU thrashing

Over the past few months, something has changed in the behavior of Safari and advertising websites. I have iStat Menus. When I fired up a new Safari window, I iStat Menus showed 10-15 seconds of ~500% CPU usage (!!!) in the Safari window. My extraordinary M1 MBP was suddenly a very ordinary – or below average – computer with sluggish performance, and I had no clue what was causing the bad behavior.

In the mean time, I ran across an old 2022 podcast episode where @Leo recommend NextDNS to deal with ad-blocking. I gave it a spin and disabled my Safari ad blocker extensions. Lo and behold, the CPU thrashing when I launched a new browser window immediately disappeared; my MBP was running the way that Tim Apple and his team intended. I had not investigated NextDNS to address my performance problems; that was a happy accident.

It looks like webpages are interacting badly with Safari ad-blocker extensions: retrying some failed operation thousands if not tens of thousands of times before giving up. I couldn’t find any hints to the bad Safari behavior; I put a topic on this message that may help others find the NextDNS solution. This is a FYI to anyone helping other Mac users dealing with this problem.

What experience do folks here have with configuring NextDNS on the computers of friends and family? The system seems a bit squirrelly. At some point, I had to flush the cookie in order to log in to my account.

In any case, I’m grateful that I finally learned about NextDNS. My Mac is much snappier, and I have one less mystery to solve. Thanks, TWiT!

I was also introduced to NextDNS by Leo on one of the TWiT shows and have use it on an Intel iMac and M2 MacBook Air. I have found it to be a great product, once I had it configured the way I like it. I have not had any issues with Safari and NextDNS; however, there are some sites that will not display with it active. If I have the issue on a particular site that I trust, I will temporarily turn it off for that site or white list that site. I do not run any other ad-blocker extensions on Safari.

I do not recommend it to family members since it is not all that easy to configure and due to the aforementioned issues with some websites. However, it someone is technically up for it and wants to deal with the issues, I highly recommend it!

I’ve been using NextDNS for a few years now. I used to run a pihole but often found that I had family members complaining that things didn’t work when they clicked on them etc, but that almost faded away to zero when I switched to NextDNS.

It’s not perfect, but it’s saved me a few times with people clicking on things that they shouldn’t have and I find it overall a lot less maintenance than my old pihole so would definitely recommend it.

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I keep meaning to setup or try an alternated DNS or PiHole. Instead I’ve mostly stuck with Quad9 and been pretty happy. I have found the odd occasion when a browser window seems to act slow/poorly (Firefox is my primary browser) and it can ALWAYS be marked up to a site behaving poorly with its Javascript and tracking.

This definitely creates a problem for The Tech Guys and Kim Komandos of the world! Do they trust a particular call-in user to have the wherewithal to deal with the nuances of NextDNS? OTOH, is the wild west of ad blockers really any less complicated? I have no idea how frequently the ad blockers create CPUs spinning out of control, but that’s a really ugly problem.

In The Space Merchants, Pohl and Kornbluth described a gruesome world where the underclass was subject to a gross deluge – and with high sound volume – of advertisements. When I read it in the 80s, the underpinnings of their SF story seemed to be almost comical. Now, I’m not so sure: there are people who are subject to far more advertising on the Internet than more-informed users. Governments are focusing on privacy, but the pervasiveness of fire-hose Internet advertising is also a real problem.

What block list do you use?

I asked Joe Kissell if ad blockers and DNS-based ad blockers were covered anywhere in the Take Control Books series. He said it’s discussed in Take Control of your Online Privacy (4e April 2019), but the information in that edition is rather dated. Joe plans to publish a 5th edition in the next few months; I plan to pick that up when it’s done. This is a tough concept; I hope this will be a good thing to refer less-experienced users on this topic.