Is there a more efficient function than the MATLAB QUANTIZ() function for modeling a non-linear quantizer?

QUANTIZ() is a search based quantizer and therefore has slow performance. Is there another MATLAB function or modeling technique known to the MATLAB community that has faster performance? When I model RF systems and stream large quantities of input sample data, overall system performance is slow when quantizing with quantiz() . I faster quantizer function would increase productivity. Thanks.