Grunt.js build process very slow in network

my build process of grunt.js is very slow in the network. To compile LESS into CSS it takes about 180 seconds ... :-( This is not normal, right? Local everything is great and the build process takes less than 1 second. This is great!

My setup: - Windows 7 - I use "Node.js command prompt" - Network server is a ReadyNAS Duo

What can I do? Network settings? Install plugin?

Greeting Jan