Well, the issue may be that JoomSEF - after generating one SEF URL - does not clear the memory, but remebers it for case that the same URLs appears on the same page once again.

So in case, there is too many URLs on a single page, the size of the memory needs may grow. (if this is the case) We will consider define an upper limit for this.

i had the same problem,
you have to check the rewrite base in .htacces have to write correctly the /subdominio/folder(joomla)

and, ,that´s all

carlos