Short version: It's the process that runs extensions and plugins like flash.
Interestingly the solution to problems with it is the same as implemented in Opera 12 years ago: Configure the browser to run plugins only when the user explicitly activates them.
I did the setting changes. Now the process monitor on my MBP (Yosemite) shows a bunch of "Google Chrome Helper" not responding in red. Not sure this has saved battery but seems battery goes out even quicker.
I am not him, but on one older Mac, I am running Snow Leopard because it's the last OS X I can run on a 32bit computer.
And yes, I know, it has all the terrible ShellShock bugs and other stuff that will never be fixed, but I just need to run some OS X software time from time and I won't buy a new Mac because of that.
And when I tried to install Linux on that, Wi-fi didn't work properly, and there were some other issues I had with I think rebooting and maybe some other hardware stuff (I know, it sounds like a cliche, but it's true)
Thanks for the honest reply. I wasn't trying to be judgemental, just trying to understand specific reasons, rather than admit the nebulous cloud of "because".
And that's pretty much why Google built Google Web Designer[0] - because advertisers are going to want their media to run on all browsers, even ones without Flash.
I do all my rewriting with a proxy (in my case glimmer blocker, though I also had to implement my own man-in-the-middle SSL tool to make it work with https connections). I simply rewrite URLs, strip referrer tags, respond with empty files for domains I don't like, and rewrite pages to remove crud. It speeds up my browsing experience immensely and coincidentally improves my privacy somewhat.
I seems brain damaged to me to do it via a browser extension since I use multiple browsers, not to mention other programs that make http/https/ftp connections (e.g. RSS reader, mail reader etc).
I've had "Click to Flash" turned on in Chrome for a while - I found running flash by default was having a measurable impact on my battery life. Turning it off makes Chrome more responsive and nets me an (anecdotal) increase in longevity when I'm away from the charger.
Flashblock on Firefox does the same thing, and I run with it rather than AdBlocker. Blocking flash removes the most painful advertising, leaving more appropriate, less in-your-face advertising as a sort of compromise for the vendors. The 'net is noticably louder when I go onto a machine without flash being blocked.
That is actually a different behavior. In Opera you have to click on a flash applet to activate it even when it's loaded automatically. The click-to-play thing however makes it so a placeholder is displayed until you click, and only then the download and integration of the applet is started. It's even configurable per site, and explicitly meant to save CPU and bandwidth.
Interestingly the solution to problems with it is the same as implemented in Opera 12 years ago: Configure the browser to run plugins only when the user explicitly activates them.