My friend asked me to post this.Might be useful , i don't know.
What he did was,
Using a Editor, take out all 16 files from the campaign itself,
11 chapters,4 interludes, 1 test map called Mystery of Friza.
Then use a program to make all 16 maps smaller ! Then put them all back together
11 chapters were all w3x files ,3 interludes were also w3x files. 1 interlude (interlude 4) and 1 test map were w3m files.
This is without proof whether it works ( There is visible change in loading time though ) so i am sorry if i am wasting your time
Oh and he did this on Beta 1.3a