Well, should I repeat myself again?
First, your last post presents different values than previous ones. The new values are completely acceptable.
To be even clearer than that, your *previous* numbers (about 30-40MB when using other tools) were also acceptable, but just a little bit higher than what I would expect. Other forum members already posted this same opinion about them (re-read the topic).
Regarding the available free memory, you have not reported anything about it, so how we would be able to understand that you indeed took note of it, or how we would be able to give you a relevant suggestion?
About the picture and the suggestions about start up items; the picture is clearly showing that you have NOT disabled the optional unnecessary startup items. So what you described doesn't correspond with the picture. Moreover, just closing or stopping the optional processes is not exactly the same for the purposes of the tests. So, again, the startup items should be temporarily suspended with the adequate method, and then reboot to start the test.
Finally, the complete clean up of ALL previous versions of avast might help, but I sincerely think this would be a waste of time. Writing all the tips I could think about a clean re-installation would take time, and performing them accordingly would take also time. In this case, according to your reports and several opinions in this topic, it is not worth it.
My current suggestion would be to wait several months for the first stable version of Avast 7 (currently only in alpha status). By then, you could run the specific avast removal utility under Windows Safe Mode, manually clean any remnant (hidden) folders containing "avast" or "alwil" in their names, and installing the new and shiny (yet to be released) Avast 7 stable. Until then, enjoy of the current security of Avast 6.