gnus-visual

gnus-visual is a variable defined in `gnus.el'.
Its value is

(summary-highlight group-highlight article-highlight mouse-face summary-menu group-menu article-menu tree-highlight menu highlight browse-menu server-menu page-marker tree-menu binary-menu pick-menu)

Documentation:
*Enable visual features.
If `visual' is disabled, there will be no menus and few faces. Most of
the visual customization options below will be ignored. Gnus will use
less space and be faster as a result.

This variable can also be a list of visual elements to switch on. For
instance, to switch off all visual things except menus, you can say:

(setq gnus-visual '(menu))

Valid elements include `summary-highlight', `group-highlight',
`article-highlight', `mouse-face', `summary-menu', `group-menu',
`article-menu', `tree-highlight', `menu', `highlight', `browse-menu',
`server-menu', `page-marker', `tree-menu', `binary-menu', and`pick-menu'.

You can customize this variable.