15. A computer-readable memory device with instructions stored thereon for generating speech employing compressed concatenation cost data, the instructions comprising: determining, based on a matrix of concatenation costs, feature vectors for speech segments, wherein the matrix of concatenation costs is constructed along a preceding speech segment and a following speech segment for each segment applying distance weighting to one of: the speech segments and at least two consecutive speech segments, wherein the distance weighting is based on feature vectors associated with the speech segments or is based on feature vectors associated with the at least two consecutive speech segments clustering the speech segments into M preceding segment and N following segment groups such that an average distance between speech segments within each group is minimized; selecting a representative speech segment for each group; generating a compressed concatenation cost matrix such that a concatenation cost between the speech segments and the at least two consecutive speech segments is approximated by a concatenation cost between a representative segment associated with the speech segments and another representative speech segment associated with the at least two consecutive speech segments; and pre-saving the compressed concatenation cost matrix for real time computations in synthesizing speech.
15. A computer-readable memory device with instructions stored thereon for generating speech employing compressed concatenation cost data, the instructions comprising: determining, based on a matrix of concatenation costs, feature vectors for speech segments, wherein the matrix of concatenation costs is constructed along a preceding speech segment and a following speech segment for each segment applying distance weighting to one of: the speech segments and at least two consecutive speech segments, wherein the distance weighting is based on feature vectors associated with the speech segments or is based on feature vectors associated with the at least two consecutive speech segments clustering the speech segments into M preceding segment and N following segment groups such that an average distance between speech segments within each group is minimized; selecting a representative speech segment for each group; generating a compressed concatenation cost matrix such that a concatenation cost between the speech segments and the at least two consecutive speech segments is approximated by a concatenation cost between a representative segment associated with the speech segments and another representative speech segment associated with the at least two consecutive speech segments; and pre-saving the compressed concatenation cost matrix for real time computations in synthesizing speech. 16. The computer-readable memory device of claim 15 , wherein the distance weighting is applied employing distance function: ∑ m = 1 n ⁢ { abs ⁡ ( cc i , m - cc j , m ) * [ K o - ( cc i , m + cc j , m ) ] } 2 , where cc i,j are concatenation costs between speech segments i and j, K o is a predefined constant, and n is a total number of the speech segments.