what is runtime broker, and why does it use so much memory?

Late at night? it must be 04.45 where you are, you madman :)

I have just been talking with a support rep from Norton, who informed me that NIS 2012 is not compatible with Windows 8 (neither is Norton 360-2012). He offered to upgrade it to NIS 2013 for free by remote connection so I let him do all the work...but it means I cannot try what you suggested - well I could but I will see if the problem has been solved with the upgrade first.

Runtime Broker is steady at around 115MB right now. I'll keep an eye on it tomorrow and let you know if the problem has been solved. You might want to upgrade yourself if it's free? I am guessing they know that there are issues as they immediately told me 2012 was not compatible with Win8

Though it may only be working for me, try this:

Disable your Norton firewall (and switch to your windows firewall) and check the status of runtime broker over a period of time. For me, turning off Bitdefender's firewall has reduced runtime broker's memory usage to quite an extent.

Uninstalling the antivirus is a probable solution (but I have already purchased mine) :-/

:D Its late night here as well (India). :p Confirm it by re-installing Norton, and monitor runtime broker as you re-install.  

After installing, try disabling your Norton firewall (enable the windows firewall if you wish) and monitor the process again. I have noticed that with my Bitdefender firewall turned off, runtime broker seems to be a little moderated (max memory usage of around 350 MB).

Hmmm....Well it's only been a few minutes but I have Word and Opera opened in desktop and mail, messaging, photos and finance apps open in start menu view. Runtime broker is only using 7.2MB of memory - it was never anywhere near that low when Norton was running so it could well be the cause of my problem. I'll report back tomorrow (late at night here in Thailand now).

Cheers

Well, I monitored the memory usage for an hour or so and it stayed at around 75MB with Norton Internet Security running. Given that, I don't think that uninstalling it would have made it easy to spot any difference in performance unless I left myself without any antivirus for a couple of days to see if it stopped the problem. I did try running a scan and runtime broker did not move from 75mb.

Later on today it started to go up again though and is currently at just over 1.1GB.

I upgraded my Windows 7 installation using the Windows 8 Pro Upgrade disk that went on sale on the 26th October, not using the RTM version either. Whilst I've been typing this I've decided to be a daredevil and uninstall Norton. I will observe runtime broker tomorrow and see if it makes any difference.