I recently wrote about my experience using Adblock Plus, the browser add-on that stops ads from appearing on any web page, and noted that an obvious part of its appeal is that web pages load incredibly quickly when they are not weighed down with ads.

I also noted that executives who work in ad tech always refuse to admit that advertising actually slows down web pages.

Two ad tech execs took me to task on Twitter, arguing that publishers are the ones to blame for slow page-load speeds. The two execs were Mark McEachran, VP product management/open platform at Rubicon Project, one of the larger adtech platforms that generates $37 million in revenue per quarter; and Mani Gandham, CEO at Instinctive, a boutique native advertising startup.

They argued that the owners of web pages could do a lot to make their pages load faster, but publishers blame slow load times on ads, and they don't talk about all the other heavy-load publisher stuff they pile into your browser. You can read our tweet debate here and here. "Pubs could've have made faster sites with ads but most don't, it's not like ad companies snuck those tags on," Gandham said.

I've talked to dozens of ad tech execs about this over the years and by and large their response sounds like this: "Pages can load instantly, if only publishers would use my company for the ads — because my company loads ads the fastest." This answer, in my opinion, isn't good enough because sophisticated publishers tend to need several different ad tech providers to do several different things at once. And that mass of tech ultimately slows down the speed at which pages load. Which is why the web is often so annoying to look at, especially if you're on a phone or last year's laptop.

But then McEachran listed for me the junk that publishers require users to swallow in order to see a typical news story: "behavior tracking javascript/pixels, videos, 'lazy load' content, infinite scroll, pre-load content, flash, fb/twitter/x ... buttons."

He has a point. Publishers are not the innocent victims of clunky ad tech here. At Business Insider, we pay a lot of attention to page load speed, but even our pages contain multiple units that all have to load.

But then Dean Murphy got my attention with an experiment he ran on the Apple tech blog iMore. He created a Safari content blocker that works a bit like Adblock. When ad content is blocked, page load time goes down from 11 seconds to 2 seconds:

With no content blocked, there are 38 3rd party scripts (scripts not hosted on the host domain) running when the homepage is opened, which takes a total of 11 seconds. ...

After turning off all 3rd party scripts, the homepage took 2 seconds to load, down from 11 seconds.

So basically, if you're looking at a site like iMore, which is heavily optimized for advertising, then each page will load 9 seconds' worth of ads in order to show news that only actually takes 2 seconds to deliver.

This isn't a freak outlier in the world of web pages. The Washington Post's pages used to take 8 seconds to load, according to Digiday. Now the Post has that down to 1.75 seconds. A lot of that — as McEachran says — is down to junk the publisher removed from its own page.

But here is the kicker. The Post's chief architect, Gregory Franczyk, still blames ad tech for slowing down page delivery:

Likewise, publishers can only do so much to reduce the resource demands of the ads on their page, which are often the most significant sources of page slowdown. That’s in part what’s given birth to the rise of ad blocking software, which can reduce data transfers by half to three quarters, according to a recent article on The Monday Note.

“We have very little control over ads that load late or slowly, but we wanted to make the core use experience as solid as possible. That’s what we have control over,” said Franczyk.

So yes, publishers do fill their pages with units and widgets that slow them down. But at some point, ad tech execs need to admit that ad tech itself slows content delivery. Anyone who uses Adblock knows the web suddenly feels lightning fast once you switch it on. It's almost like having a new computer — no more spinning wheels or minutes-long crashes while you wonder whether you're going to force-quit or reboot just to see a page.

Until I hear an ad tech exec say, on the record, that ad tech itself slows down pages, then ad tech wil remain part of the ad-blocking problem and not part of its solution.