A Faster way of Directory walking instead of os.listdir?

I am trying to improve performance of elfinder , an ajax based file manager(elRTE.ru) .

It uses os.listdir in a recurisve to walk through all directories recursively and having a performance hit (like listing a dir with 3000 + files takes 7 seconds ) ..

I am trying to improve performance for it here is it's walking function:

        for d in os.listdir(path):
            pd = os.path.join(path, d)
            if os.path.isdir(pd) and not os.path.islink(pd) and self.__isAccepted(d):
                tree['dirs'].append(self.__tree(pd))

My questions are :

1. If i change os.walk instead of os.listdir , would it improve performance?
2. how about using dircache.listdir() ? cache WHOLE directory/subdir contents at the initial request and return cache results , if theres no new files uploaded or no changes in file?
3. Is there any other method of Directory walking which is faster?
4. Any Other Server Side file browser which is fast written in python (but i prefer to make this one fast)?