gnus-summary-display-while-building

gnus-summary-display-while-building is a variable defined in `gnus-sum.el'.
Its value is

nil

Documentation:
If non-nil, show and update the summary buffer as it's being built.
If the value is t, update the buffer after every line is inserted. If
the value is an integer (N), update the display every N lines.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.