You can speed up the access to nodes of a large Info file by giving it a tags table. Unlike the tags table for a program, the tags table for an Info file lives inside the file itself and is used automatically whenever Info reads in the file.
To make a tags table, go to a node in the file using Emacs Info mode and type
M-x Info-tagify. Then you must use C-x C-s to save the
file. Info files produced by the makeinfo command that is part
of the Texinfo package always have tags tables to begin with.
Once the Info file has a tags table, you must make certain it is up
to date. If you edit an Info file directly (as opposed to editing its
Texinfo source), and, as a result of deletion of text, any node moves back
more than a thousand characters in the file from the position
recorded in the tags table, Info will no longer be able to find that
node. To update the tags table, use the Info-tagify command
again.
An Info file tags table appears at the end of the file and looks like this:
^_^L
Tag Table:
File: info, Node: Cross-refs^?21419
File: info, Node: Tags^?22145
^_
End Tag Table
Note that it contains one line per node, and this line contains
the beginning of the node's header (ending just after the node name),
a DEL character, and the character position in the file of the
beginning of the node.