git repack command on larger pack file

Hi,
   I ran git repack on a single larger repository abc.git where the pack
file size 34 GB. Generally it used to take 20-25 minutes in my server to
complete the repacking. During repacking I noticed, disk usage was more, So
I thought of splitting the pack file into 4 GB chunks. I used the following
command to do repacking.
   git repack -A -b -d -q --depth=50 --window=10 abc.git

   After adding --max-pack-size=4g to the above command again I ran to split
pack files..
   git repack -A -b -d -q --depth=50 --window=10 --max-pack-size=4g abc.git
 
   When I finished running, I found 12 pack files with each 4 GB and the
size is 48 GB. Now my disk usage has increased by 14 GB. Again, I ran to
check the performance, but the size (48 GB) and time to repacking takes
another 35 minutes more. Why this issue? If we split a larger pack file,
repacking takes more time with more disk usage for storing pack files. Any
thoughts on this why this happens?

Thanks,
Sivakumar Selvam.