These are the results I get (wordlist contains 351,100 records)
$t1 = microtime(1);
$res = $db->query("SELECT word FROM wordlist WHERE MATCH (word) AGAINST ('sang*' IN BOOLEAN MODE)");
$t2 = microtime(1);
printf('Query 1 : %0.4f seconds<br>', $t2 - $t1);
$t1 = microtime(1);
$res = $db->query("SELECT word FROM wordlist WHERE word LIKE 'sang%'");
$t2 = microtime(1);
printf('Query 2 : %0.4f seconds<br>', $t2 - $t1);
results (74 words found)
Query 1 : 0.0026 seconds
Query 2 : 0.0005 seconds