gnus: The Active File
1.8 The Active File
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When Gnus starts, or indeed whenever it tries to determine whether new
articles have arrived, it reads the active file. This is a very large
file that lists all the active groups and articles on the server.
Before examining the active file, Gnus deletes all lines that match
the regexp ‘gnus-ignored-newsgroups’. This is done primarily to reject
any groups with bogus names, but you can use this variable to make Gnus
ignore hierarchies you aren’t ever interested in. However, this is not
recommended. In fact, it’s highly discouraged. Instead, 
New
Groups for an overview of other variables that can be used instead.
The active file can be rather Huge, so if you have a slow network,
you can set ‘gnus-read-active-file’ to ‘nil’ to prevent Gnus from
reading the active file. This variable is ‘some’ by default.
Gnus will try to make do by getting information just on the groups
that you actually subscribe to.
Note that if you subscribe to lots and lots of groups, setting this
variable to ‘nil’ will probably make Gnus slower, not faster. At
present, having this variable ‘nil’ will slow Gnus down considerably,
unless you read news over a 2400 baud modem.
This variable can also have the value ‘some’. Gnus will then attempt
to read active info only on the subscribed groups. On some servers this
is quite fast (on sparkling, brand new INN servers that support the
‘LIST ACTIVE group’ command), on others this isn’t fast at all. In any
case, ‘some’ should be faster than ‘nil’, and is certainly faster than
‘t’ over slow lines.
Some news servers (old versions of Leafnode and old versions of INN,
for instance) do not support the ‘LIST ACTIVE group’. For these
servers, ‘nil’ is probably the most efficient value for this variable.
If this variable is ‘nil’, Gnus will ask for group info in total
lock-step, which isn’t very fast. If it is ‘some’ and you use an NNTP
server, Gnus will pump out commands as fast as it can, and read all the
replies in one swoop. This will normally result in better performance,
but if the server does not support the aforementioned ‘LIST ACTIVE
group’ command, this isn’t very nice to the server.
If you think that starting up Gnus takes too long, try all the three
different values for this variable and see what works best for you.
In any case, if you use ‘some’ or ‘nil’, you should definitely kill
all groups that you aren’t interested in to speed things up.
Note that this variable also affects active file retrieval from
secondary select methods.
Info Catalog
gnus: Auto Save
gnus: Starting Up
gnus: Startup Variables