optimizing code

[BVBA NuKey Music]

Is it possible to make the following code run faster?
clear
%example format of testfile
%Dec-01-13:18:59 24.8 +1.54415760E-01 7.387060E-06 2.579755E+00
%Dec-01-13:19:26 24.8 +1.54396330E-01 7.389665E-06 2.580398E+00
%Dec-01-13:19:53 24.8 +1.54362790E-01 7.391425E-06 2.580347E+00
fmt = "%s %f %f %f %f";
[A, B, C, D, E] = textread("testfile", fmt);
y=[(datenum(cell2mat(A),'mmm-dd-HH:MM:SS')-datenum(cell2mat(A(1)),'mmm-dd-HH:MM:SS'))*24*60*60
B C D E];
save('outputfile','y');

thanks in advance
nukey