  Ongoing observations of the Cosmic Microwave Background, such as the MAXIMA
and BOOMERanG projects, are providing datasets of unprecedented quality and
ever-increasing size. Exact analysis of the data they produce is a serious
computational challenge, currently scaling as the number of sky pixels squared
in memory and cubed in time. Here we discuss the origins of these scaling
relations and their implications for our efforts to extract precise
cosmological parameters from observations of the CMB.
