1. A method for performance by at least one processing unit in compressing data vectors sequentially in a respective compression pass said method comprising: said at least one processing unit mapping a current data vector to at least one current code vector of at least one codebook in at least one quantization stage; said at least one processing unit reordering said at least one codebook taking account of at least one intermediate result from a current compression pass and at least one intermediate result from a preceding compression pass, wherein said intermediate result from a preceding compression pass comprises at least one of: (a) a codevector selected for two or more quantization stages of a multi-stage quantizer during the preceding compression pass and (b) a predicted vector from the preceding compression pass; and providing at least one codebook index that is associated in said at least one reordered codebook to said at least one current code vector; wherein said reordering is based at least upon a sum of code vectors respectively selected at earlier stages during the current compression pass.