I actually had the reverse problem. I wanted to increase the delay time, because I detest sub-menus opening up before I click them.
I found that the value can be more than 4000 (4 seconds). I tried 10000, and it was about 10 seconds. Then I wondered if a negative value might make it infinite, i.e. not open the sub-menu until I click. Sure enough, I set it to -1, and that now seems to occur.