gvim taking so long to display 'all tags' using g ctrl-]

Question

I am navigating c++ code using gvim and ctags. Size of the ctags file is 3.5 GB. ctrl-] is working pretty quick, but g+ctrl-] is taking nearly 5 seconds, which I think is too much (that is too much time for searching a sorted ctgas file!). Any suggestions to improve speed?

My .gvimrc:

set gcr=n-c-v:blinkoff0         " it switches off cursor blinks
set lines=52 columns=120        " Sets the geometry of gui window.
colorscheme default             " desert load the color scheme of choice
set nocompatible                " This must be first, because it changes other options as a side effect.
set ic
set backspace=indent,eol,start  " allow backspacing over everything in insert mode
set history=10000               " keep 100 lines of command line history
set showcmd                     " display incomplete commands
set incsearch                   " do incremental searching
set et
set paste
set ruler                   

Answer 1

When you have 'ignorecase' on, Vim mostly needs to perform a linear search of the tags database, instead of a much faster binary search. You may be able to avoid that penalty with a proper tags database that indicates case-folded sorting by this line:

!_TAG_FILE_SORTED   2

See :help 'tagbsearch' for all the details.

Answer 2

Problem is due to ic! When I removed ic(ie set noic), then the speed was drastically improved. g+ctrl-] is as fast as ctrl-] now.