Hi Niall -
There is a bit of "sleep" code in spider.php that prevents phpDig from requesting pages too quickly from web hosts. You can find this line and change the sleep time of 5 seconds between links to your choosing:
PHP Code:
// Spidering ...
while($level <= $limit) {
sleep(5);
This will help make spidering faster, as long as the site your spidering doesn't mind the increased load.