When adding an image to Moxie Manager there are a few options in which we can use to optimize said picture. This helps in particular with page loading times.

Resizing the image through Moxie Manager

After we have uploaded the image, we can edit it. First select the image by clicking the checkbox:

Then click the "Manage", a drop down will appear. Click "Edit":

You will be brought to the edit image screen. Click "Resize":

Options will open up at the top of the window. Change the dimensions and hit "Apply":

You will then have to hit "Save" and then give the new image a new name or overwrite the image you are edting:

You will now be able to use the newly resized image!

Also see "Crop Images with the file manager"