Far, FAR less than the page- and cpu- weight of the crap they block. As in, it's a hugely transformative experience for web browsing, even for many "normal" sites that aren't merely social media click-farms.
I'll add to the list: Uninstall Flash completely. For much of the crowd here, that's probably a no-brainer after the recent spate of Flash zero-days, but still.
I suspect that depends entirely on the site you are visiting. This one for example loads almost nothing so running additional plugins will indeed add overhead.
Many of the sites that I use the most load very little unneeded resources and I tend to leave lots of tabs open while working.
Granted, I am not a "normal" web user, but so far all of the responses to my question have brushed it off as unimportant. My suspicion is then that they don't know the answer, which makes the brush off unconvincing.
> I suspect that depends entirely on the site you are visiting.
Yes, that's obviously true. But for my part, whatever overhead these tools do add is low enough that, even for no-crap sites like HN, if I can notice it at all it's within the page-load-latency noise threshold. Moveover, the increased browser stability, laptop battery life, etc. is an overwhelming win.
FWIW, I just fired up Chrome on HN and messed around with the dev tools a bit to see if there was any obvious overhead. Without taking the time for anything like rigorous analysis, loading HN with all extensions disabled vs. uBlock Origin and Privacy Badger had no immediately obvious effect on page load+render times. The superficial results agreed with my intuition: I'd have to collect data and run an analysis to uncover any added page load latency.
