The gmail app screen is blank until you press the menu key, correct?
If so, it may be an application bug, though I don't see that on my 7100t. Try a power cycle. Then try a hard-reset (remove battery for 15 seconds).
If the issue is with bandwidth, there's something you can do:
By default, the text of the first few emails are preloaded when you launch the app, or select a new label. That means a lot of data transfer. You can turn off preloading with:
Menu: More->Settings Uncheck Preload
I see a noticable decrease in load time.