setting syntax on in vim with large C file makes complete very slow

Question

when I have syntax on in a large C file (about 8000) lines the completion ctrl-p and ctrl-n are very slow (more than 20). When I turn syntax off then completion takes less than a second.

Any ideas on how to solve this?

Thanks!

EDIT:

I figured out a minimal way of reproducing this behaviour: with an empty .vimrc and .vim folder the only changed settings are

:set syntax on
:set foldmethod=syntax

and a large C file to edit, completion (and even general editing) becomes very very slow.

Second Edit:

I now realized that this behavior has due to the fact that I was using a beta version. I am not sure if I should delete this question altogether, or leave it so if others have the same problem can have some clue about it.

Thanks.

Answer 1

I'm guessing your completion is being adjusted by the syntax highlighting file. To see if this is the case, and make completion lean and fast regardless, try

:set complete=.

which will make completion only use the current file.

read more about the complete options with

:help 'complete'