I haven't checked today, but the experience on mobile ever since the redesign has been terrible, generally unusable. I just hadn't complained about it until somebody woke up the thread saying it was laggy and I decided to finally say something.
I've always been on android, and it hasn't mattered what version or what browser. Chrome, firefox, built-in android browser, it's always really, really bad.
I'll add in that even browsing on a desktop computer is often laggy. I feel like this experience isn't usual, even with other sites that are ad-heavy.. so I wonder if it's less the existence of the ads, and more an implementation issue somewhere. I wish I could offer more in terms of looking into it, but I don't have experience with implementing ad systems in websites. I'm not sure if it's typical for sites with ads to be constantly making a crap ton of web calls downloading content, which appears to be the case when I monitor the network activity through Chrome's developer console. There's also a lot of warnings and errors when loading stuff in the console. Perhaps the developer can monitor some of that stuff and try to either update the ad systems to fix any bugs on their end, or make sure all the necessary scripts are in place, I dunno.