This script was tested and works on OpenSim version 0.7.4!

collision_preloader.lsl
///////////////////////////////////////////////////////////////////////////
//  Copyright (C) Wizardry and Steamworks 2013 - License: GNU GPLv3      //
//  Please see: http://www.gnu.org/licenses/gpl.html for legal details,  //
//  rights of fair usage, the disclaimer and warranty conditions.        //
///////////////////////////////////////////////////////////////////////////
 
list hissList = [ "Hiss_0", "Hiss_1", "Hiss_2", "Hiss_3", "Hiss_4", "Hiss_5", "Hiss_6", "Hiss_7", "Hiss_8", "Hiss_9" ];
 
default
{
    state_entry() {
        llSetTimerEvent(.1);
    }
 
    timer() {
        string hiss = llList2String(hissList, 0);
        hissList = llDeleteSubList(hissList, 0, 0);
        hissList += hiss;
        llPreloadSound(hiss);
    }
}