Hi there, cairngorm isn't necessary for the remoting.
Remoting is almost always gonna be faster except in some cases when
the remoting adds overhead by the way it works. If you wanna see
metrics about http service vs remoting you can take a look at
http://www.jamesward.com/census/,and if you wanna know more about performance issues and tuning I
strongly recommend you to watch James Ward's 08 Max Session Working
with Data in Flex