Display dynamic table of checkbox in 3 columns in php - php

Question

I have a database table of subjects. I have a web page that displays the list of subjects in 3 columns so that a user can select subjects using a checkbox. The challenge I have is it takes a long time for the list to display. The code is below:
<?php
$subjects = mysql_query("select id, name from subjects WHERE exam_type_id='0' OR exam_type_id='$exam_type_id' ORDER BY name");
$noOfSubjects = mysql_num_rows($subjects);
?>
<form name="form1" method="post" action="" class="FormCss" onsubmit=" return window.confirm('You are about to submit selected subjects. If you are not sure, cancel');">
<table>
<tr class="FormLabel2">
<td align="left" colspan="3" valign="top"></td>
</tr>
<?php
$i = 1;
while ($subject = mysql_fetch_array($subjects)){
// if it is a value that is supposed to be in the 1st cell of a row, print tr
if ($i==1 || $i==4 || $i==7 || $i== 10){
?>
<tr>
<?php
}
// print a td if value is not suppose to be the last on a row
if ($i%3 !=0){
?>
<td><input type="checkbox" name="subject[]"
value="<?php echo $subject['id']?>" <?php if (isCompulsoryMockSubject($subject['id'])){?> onclick="return false;" onkeydown="return false;" <?php }else{}?> <?php if (isCompulsoryMockSubject($subject['id'])){?> CHECKED="checked" <?php }else{}?> <?php if (hasSelectedSubject($_SESSION['candidate_id'], $exam_type_id, $subject['id'])){?> checked="checked" <?php }?>><?php echo $subject['name'];?>
</td>
<?php
}else{
// end the row
?>
<td><input type="checkbox" name="subject[]"
value="<?php echo $subject['id']?>" <?php if (isCompulsoryMockSubject($subject['id'])){?> onclick="return false;" onkeydown="return false;" <?php }?> <?php if (isCompulsoryMockSubject($subject['id'])){?> CHECKED="checked" <?php }else{}?> <?php if (hasSelectedSubject($_SESSION['candidate_id'], $exam_type_id, $subject['id'])){?> checked="checked" <?php }?>><?php echo $subject['name'];?>
</td>
</tr>
<?php
}
$i++;
}
?>
<tr>
<td width="34%" align="left" valign="top" class="FormLabel2"> </td>
<td width="33%" align="left" valign="top"><span
class="FormLabel2"> <input name="Submit" type="submit"
class="loginInputSubmit" value="Save"> </span></td>
<td width="33%" align="left" valign="top"> </td>
</tr>
<tr>
<td align="left" valign="top" class="FormLabel2"> </td>
<td colspan="2" align="right" valign="top" class="FormLabel2"> </td>
</tr>
</table>
</form>