Pull/ fetch more than one submodule in parallel

I have around 25 Submodules in a big Project. 
If possible do the git calls to Submodules in parallel.

The Submodules have nearly never Changes but come from different Locations and it seems most of the runtime is lost in the Time for Authentification.

git.exe -c credential.helper= -c "credential.helper=C:/Program\ Files/SmartGit/bin/smartgitc.exe --credential=somenumber" -c credential.useHttpPath=true fetch --progress --prune --recurse-submodules=no origin