Had similar problems a while back with McAffee Anti-virus. Mine was both a CPU and memory problem, but then again the CPU was only an old 1.8GHz iBook G4 (rest its soul). So, it may be a program running in the background it may not be. Have you recently installed a lot of new programs and have anti-virus software? if so, give it some time. Is this a new computer and Spotlight is indexing new information you just put onto it? if so, give it some time, and it should return to normal. If not, you'll have to ask one of the real pros around here.😀