In “recent comments”, Gravatars are shown not from the cache

This code last comments in sidebar.

And there gravatars are requested from the server, not from the cache.

$comments = get_comments('status=approve&number=5'); ?>
<ul>
<?php foreach ($comments as $comment) { ?>
    <li><?php
        $title = get_the_title($comment->post_ID);
        echo get_avatar( $comment, '42' );
        echo strip_tags($comment->comment_author);
        ?>&nbsp;<?php
        echo wp_html_excerpt( $comment->comment_content, 35 ); ?>
        <a href="<?php echo get_permalink($comment->post_ID); ?>" rel="external nofollow" title="<?php echo $title; ?>"> <?php echo $title; ?> </a>
    </li>
<?php }  ?>

I beg you to correct this.

Sorry for my English.