This paper studies noise reduction for computational efficiency improvements in a statistical learning method for text categorization, the Linear Least Squares Fit (LLSF) mapping. Multiple noise reduction strategies are proposedand evaluated,including: an aggressive removal of “non-informative words” from texts before training; the use of a truncated singular value decomposition to cut off noisy “latentsemantic structures” during training;the elimination of non-influential components in the LLSF solution (a word-concept association matrix) after training. Text collections in different domains were used for evaluation. Significant improvements in computational efficiency without losing categorization accuracy were evident in the testing results.