<?php if ( has_nav_menu( ‘bar’ ) ) :  wp_nav_menu( array( ‘theme_location’ => ‘bar’, ‘container’=>’false’,’items_wrap’ => ‘%3$s’,’depth’ => 2 ) ); else : ?>
<?php wp_list_pages( ‘title_li=&depth=2’ ); ?>
<?php endif; ?>

This modification removes CSS3 validation error , but does not seem to affect the IE8 performance.