Did your eyes sick when see the icon on the Application shortcut on Gnome3 shell is too big? I feel it. Then I googling around and found the tutorial that we can edit some setting on the Gnome3 shell. By using 'gedit' software we need to edit some parameter in the 'gnome-shell.css' file. In this case we only need to change some value that related to the icon size. If you interested to try, you can follow instruction below,
1. Open terminal and run this command, sudo gedit /usr/share/gnome-shell/theme/gnome-shell.css. If you can run it, check either gedit had installed on your system or not.
2. Search for 'icon-grid' it will bring you to the parameter. Note your standard parameter for icon-grid spacing, shell-grid-item-size and icon-size.
3. Change the value of the parameter like you see on the screenshot . Actually this is depend on your screen resolution. You can change the value suitable to your display setting. Save it by click on save button. Close 'gedit' to log out.
4. Log out then log in back to see the different.
There some item that we can play on the gnome-shell.css file. But do it on your own risk.