If you are the store owner and your store is growing, you will meet the speed issue. It doesn't matter by which reason - it can be a big products database or the visitors amount.
It's good if you are checking the store speed from time to time - for example by this service. But in any case you will start to receive the customer complains.
The first thing in this case - check the actual speed of the scripts. It's pretty easy to insert the following:
if ($_GET['mct']) echo microtime().'<br>';
to the home.php. It should be insert in the following places:
<?php if ($_GET['mct']) echo microtime().'<br>'; ......... if ($_GET['mct']) echo microtime().'<br>'; func_display("customer/home.tpl",$smarty); if ($_GET['mct']) echo microtime().'<br>'; ?>
And it will give the ability to check the smarty and general loading speed. You should simply load the home page of your store with the mct get param:
<store-url>/home.php?mct=1
If the general time is bigger then 2 sec - the speed up is required. In the justbedding.com.au case it was about 5 sec, so we are going to the small changes stage.