Reduce image size, even with preview, using Trout GIF Optimizer
Trout’s GIF Optimizer allows you to reduce the size of a gif file without noticeable changes in its appearance.
You can preview the result of the optimization before saving. You can also change the background color of the Preview panes, in order to simulate your publication’s environment.
You can apply color reduction selecting between various methods, including palette.
Note that there is no button or menu option to save a color-optimized file! You need to right-click on the image at the preview pane and select the save option!