How to make elisp(cedet) working faster?

How to make elisp(cedet) working faster?

[lu]

Hi
I'm using cedet (1.0pre3 or pre4) to write c program.
When I press M-x semantic-ia-complete-symbol-menu,
It needs about 30 seconds to popup symbol-menu.

for example:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
main()
{
....
....
str(at this point, Press M-x semantic-ia-complete-symbol-menu
It always need abount 30 seconds to popup symbol-menu.
)

Is there anyway to make it working faster?

The following is my setting.
;;Cedet
(setq semantic-load-turn-everything-on t)
(load-file (concat plugin_path "/common/cedet.el"))
(setq semantic-idle-scheduler-idle-time 432000)

(setq semanticdb-default-save-directory (expand-file-name "~/semanticdb"))
;; Select one of the following
(semantic-load-enable-code-helpers)
;;(semantic-load-enable-guady-code-helpers)
;;(semantic-load-enable-excessive-code-helpers)
;; Enable this if you develop in semantic, or develop grammars
;; (semantic-load-enable-semantic-debugging-helpers)
;; ---------------------------------------
(setq semanticdb-search-system-databases t)

;; (setq semanticdb-project-roots
;; (list
;; (expand-file-name "/")))
(add-hook 'c-mode-common-hook
(lambda ()
(setq semanticdb-project-system-databases
(list (semanticdb-create-database
semanticdb-new-database-class
"/usr/include")))))
(setq semantic-ia-completion-menu-format-tag-function
'semantic-format-tag-prototype)
(setq semanticdb-find-default-throttle '(project unloaded system recursive))