php artisan command becomes slow in WAMP 3.0

I used WAMP 3.0 for my local environment (Windows 7). I didn't change anything on the environment, and the "php artisan" command suddenly became very slow. The command would not return with a display within minutes.

I switched back and forth on PHP, 5.6.16 and 7.0.0, both supported in WAMP 3.0. And they are all the same. How can I solve this problem? Thanks!