I am loving Windows 8 RTM. It's very quick and it uses hardly any resources. Look at the pics below. I haven't "tweaked" any services or startup programs. Default install with all my programs installed. When was the last time your 64-bit Windows install had under 30 services running and using less than 800MB RAM?
Yes and more. One of the cool features I found is a built in "virtual drive". You can mount ISO images to a virtual drive and when you are done, the services disables until you need it again itself so it's not wasting resources. A lot of services work like that in Win8. They are "triggered" starts, with auto shut off. Like Windows Update for example. I have automatic updates turned off. So the WU service is idle (not running) until I manually check for updates. When it's done, the service shuts off until I "trigger" it again.
By triggered you are basically saying that they have gone back in time to the days when you had TSR's heheh. For those that don't know the acronym, TSR stands for Terminate and Stay Resident. This was a way to get around the memory limits of old DOS systems and Windows 3.1. It worked well back then for the most part, so it should work well now. If you read up on Windows 8, it doesn't actually shut down any program completely, it puts it into a low resource, low priority sleep mode basically. Windows 8 will flush memory caches and free up ram that isn't required to keep the program resident. Though not perfect it would allow for less resources to be used until the program is actually being used. The biggest issue with this would be if you are not cycling your system on a regular basis and use a lot of different programs all the time. You could end up with 10's or 100's of programs sleeping in the background using resources depending on what you use your computer for. There are ways however to completely close a program, but not an easy self evident one.
But still that should be no issue until you want to launch them all. But without TSR you would also end up running out of memory in such situation Good thing is, all apps in sleep mode will also be lighter on CPU cycles.
They have changed things a little then since I tried it. I have run 3ds Max and had it remain running and that is definitely not a Metro app.