I have the full version of KDE and GNOME. No UNE installed at all. My
netbook has 1 GB of DDR2 RAM, 1.6 Ghz Atom Processor and Intel graphics.
Nothing fancy.

UNE has scaled down graphics (smaller screen size and font) and has a
simplified interface with less need for virtual desktops, but it is not
faster than GNOME. The reason is that GNOME uses Metacity and UNE uses
Mutter which has performance issues. When the new version of Ubuntu comes
out it will have Unity as the default desktop environment, but it will not
use Mutter because it is a clunker. It will have either Compiz (for
compositing) or Metacity (without compositing). So if you are finding Unity
works better that is the opposite of what most people find and the opposite
of what Canonical thinks, otherwise they woulod still be using Mutter.

I have used KDE's Netbook interface and prefer it to Unity, but still prefer
GNOME with either Metacity or Compiz. There is an application in the
repositories called Fusion Icon and when you run it it loads to the
notication area and it allows you to switch window managers and decorators,
so you can go between Metacity and Compiz and see what works better. You cna
even use KDE decorations in GNOME and vice versa. I don't know if it would
show Mutter, but it is worth a try.

When you installed KDE did it install the full KDE interface or the netbook
one? They are identical under the surface. It installed the Netbook version
for me with my asking it to. I had a hard time trying to figure out how to
remove it and change it to regular KDE. Whether I run KDE or GNOME I change
to font and icon size (smaller) and turn on anti-aliasing. This works well
for me, but every user is different. I prefer KDE because I love to
customise rather than go with the stock installation and everything in KDE
is changeable. I always find it strange that GNOME users criticise KDE for
this when they don't plan on changing it anyway.

I switched to KDE 4.6 on my desktop computer a couple of days ago. It is
really slick. I stayed with 4.5 on my netbook, though. KDE, GNOME and Unity
are all headed in a similar direction and changing the way we work. They are
all moving away from spatial desktops to conceptual desktops. They all call
it Activities. KDE's is a little different in that you can use both spatial
and conceptual together. That's what I like about KDE. You keep on getting
more and lose nothing in the process. Unity and GNOME Shell give up spatial
for Activities, or at least they make it harder to use both. I think GNOME
and Unity users are going to have a bit of adjustment to make. KDE users can
just keep working along as always and can try the new features or keep it as
it is.