Well, the rumoured 0.5 GB RAM allocated to the OS would have made the OS more clunky and slow. If anything, this should be helpful for the OS performance since it has more resources to work with.
Amount of ram =|= speed of the OS. You can create fast and very useful OS even if you have very little ram, and you can do it even if the ram is slow.
http://images.anandtech.com/doci/6297/membandwidth_575px.png
[Just dont ask Ninendo to create it ]