Added ETag support and increased caching settings to try and speed the system up. Result of a YSlow audit.
<div class="tblholder">
<table border="0" width="100%" cellspacing="1" cellpadding="4">
<tr>
<th colspan="2" style="text-align: left;">{DATETIME}</th>
</tr>
<tr>
<td style="width: 120px; height: 100%;" rowspan="4" valign="top" class="row1<!-- BEGIN is_friend --> row1_green<!-- END is_friend --><!-- BEGIN is_foe --> row1_red<!-- END is_foe -->">
<table border="0" width="100%" style="height: 100%;" cellspacing="0" cellpadding="0">
<tr>
<td valign="top" class="row1<!-- BEGIN is_friend --> row1_green<!-- END is_friend --><!-- BEGIN is_foe --> row1_red<!-- END is_foe -->">
<b>{NAME}</b><br />
<small>{USER_LEVEL}</small>
<!-- BEGIN user_has_avatar -->
<div class="avatar">
<a href="{USERPAGE_LINK}">
<img alt="{AVATAR_ALT}" src="{AVATAR_URL}" style="border-width: 0px;" />
</a>
</div>
<!-- END user_has_avatar -->
</td>
</tr>
<tr>
<td valign="bottom" class="row1<!-- BEGIN is_friend --> row1_green<!-- END is_friend --><!-- BEGIN is_foe --> row1_red<!-- END is_foe -->">
{SEND_PM_LINK} {ADD_BUDDY_LINK}
</td>
</tr>
</table>
</td>
<td class="row2">
<b>{lang:comment_lbl_subject}</b> <span id="subject_{ID}">{SUBJECT}</span>
</td>
</tr>
<tr>
<td class="row3">
<div id="comment_{ID}">{DATA}</div>
<!-- BEGIN signature -->
<hr style="margin-left: 1em; width: 200px;" />
{SIGNATURE}
<!-- END signature -->
</td>
</tr>
<!-- BEGIN can_edit -->
<tr>
<td class="row2">
[ {EDIT_LINK} | {DELETE_LINK} ]
</td>
</tr>
<!-- END can_edit -->
<!-- BEGIN auth_mod -->
<tr>
<td class="row1">
<b>{lang:comment_lbl_mod_options}</b> {MOD_APPROVE_LINK} {MOD_DELETE_LINK} | {MOD_IP_LINK}
</td>
</tr>
<!-- END auth_mod -->
</table>
</div>
<br />