I am also fronted developer and facing same problem, it's because of server side compilation mode.
Please try following method, may be it's helpful and you don't need grunt cmd also so it's save your time also
go to
store > Configuration > Advanced > Developer > Front-end development workflow
and change workflow type to Client side less compilation
Now go to your Magento installed directory and manually delete following folders
1. pub\static\frontend\Magento (remove all theme folders)
2. var\ (remove all items)
now edit any less file and check it.
no need to run any grunt CMD direct Refresh your browser may be it's working fine.
also please install below add-on in firefox
https://addons.mozilla.org/en-US/firefox/user/simonedeponti/?src=api
it's show you direct less file path in browser when you inspect elements.
I think it's better way to save time.