a snippet in EmacsWiki isn't compatible

[TailorSchmitt]

I use this snippet from EmacsWiki(https://www.emacswiki.org/emacs/Smex):
;;; Filters ido-matches setting acronynm matches in front of the results
(defadvice ido-set-matches-1 (after ido-smex-acronym-matches activate)
(if (and (fboundp 'smex-already-running) (smex-already-running)
(> (length ido-text) 1))
(let ((regex (concat "^" (mapconcat 'char-to-string ido-text "[^-]-")))
(acronym-matches (list))
(remove-regexes '("-menu-")))
;; Creating the list of the results to be set as first
(dolist (item items)
(if (string-match ido-text item) ;; exact match
(add-to-list 'acronym-matches item)
(if (string-match (concat regex "[^-]$") item) ;; strict match
(add-to-list 'acronym-matches item)
(if (string-match regex item) ;; appending relaxed match
(add-to-list 'acronym-matches item t)))))

    ;; Filtering ad-return-value
    (dolist (to_remove remove-regexes)
      (setq ad-return-value
            (delete-if (lambda (item)
                         (string-match to_remove item))
                       ad-return-value)))

    ;; Creating resulting list
    (setq ad-return-value
          (append acronym-matches
                  ad-return-value))

    (delete-dups ad-return-value)
    (reverse ad-return-value))))

When I use Emacs 24.5, it works quite fine and helps me a lot. However, there seem to be some strange errors after I update Emacs 24.5 to Emacs pretest 25.0.94. For example, I can only type three letters after I hit M-x. The fourth letter will overwrite the third letter.