php script optimisation - php

Question

I'm not a php guru, need your help.
I have a php form with select menu. The menu is formed form the customers table e-mails. I've used the following code:
for($i = 0; $i < sizeof($customers_table); $i++){
echo '<option value="'.$customers_table[$i]['id'].'">'.$customers_table[$i]['email'].'</option>';
}
The base is rather big, so it takes time to form the option field. Is there any way to optimize the script so it will work faster.
Thank you.

Answer 1

As the size does not change, store it:
$size = sizeof($customers_table);
for ($i = 0; $i < $size; $i++) {
echo '<option value="'.$customers_table[$i]['id'].'">'.$customers_table[$i]['email'].'</option>';
}
Then you can shorten the loop condition and reduce the array access:
$i = $size = sizeof($customers_table);
while ($i) {
$table = $customers_table[$size-$i--];
echo '<option value="'.$table['id'].'">'.$table['email'].'</option>';
}
Next part is the echo statement which can just output instead of concatinating strings before outputting them:
$i = $size = sizeof($customers_table);
while ($i) {
$table = $customers_table[$size-$i--];
echo '<option value="', $table['id'], '">', $table['email'], '</option>';
}
If this makes a difference, you need to metric. The largest time taken might be the amount of HTML you send to the browser. But that would be out of the scope of this fragment.
To improve the overall readability of the code I suggest using foreach:
foreach ($customer_table as $row)
{
echo '<option value="', $table['id'], '">', $table['email'], '</option>';
}
This generally is pretty fast as well.

Answer 2

As Andy said, it's not a good idea to optimize this script that way.
If you want significant time changes, you have to rethink the problem.
You have a list of customers, and if there is a problem of time, I assume that there are a lot. So, a drop-down list would be useless for a user.
There are other solutions, more efficient :
Using a sort of caching > Your html code will always be the same, so you just need to do the loop once, when you add, delete or update a customer, and store the html code in a script or database. So, each time your page is reloaded, you just have to retrieve the html code.
Do not load all the customers > The user doesn't need to see all the customers, just the ones he's interested in, so with some Ajax you can load the options while the user is typing (see this for example: jQuery Autocomplete)
Those solutions are the best for optimization, and if you combine them (caching and autocomplete above 3 characters typed) it will be even better for user experience too.