Good point. Thanks for mentioning that.
Each user can change their settings to allow or prevent avatars, signatures, or all images, to speed up the loading of pages if you have a slow connection, or are accessing via phone or mobile device.
Here is how-
Click on the UserCP link in the black banner across the top
Then click the Edit Options link in the left column.
Then scroll about halfway down to the Thread Display Options.
Then uncheck the option to Show Avatars.
You can also uncheck the Show Signatures, or Show Images if needed.