A quick example of transients

gistfile1.txt

// set the variable $instagram_data to the data previously stored as a transient.
// if the transient has expired or there is not data, the variable will be empty.
$instagram_data = get_transient('myprefix_instagram_data');


// if the variable is empty, we need to get the new data from instagram
// But if it is not empty, it will skip all the steps inside this loop, saving time.

if ( !$instagram_data ) {

	// Do stuff here to get instagram information
	// This is where your site contacts instagram to get information on reent photos
	// Generally something that takes time tdo
	
	$new_data  = {DO STUFF HERE};
	
	// OK, so now we have our data that we can use in our script. 
	// But before we use it, we'll save the transient for later use
	//
	// This sets the transient, which is stored in the WordPress database or in object cache if yuou have 
	// it turned on for your web site (can happen through caching plugins and web config)	
  	//
  	// The parts to the data are:
  	// 'myprefix_instagram_data' - the name of the transient stored
  	// $instagram_data - the data gotten in the DO STUFF HERE section
  	// '60' - the number of seconds that the transient will be valid until it expires.
  	//
  	// To figure out the number of seconds, I just google "Convert 5 hours to seconds"
  	// This is set to three hours (10800 seconds)
  
  	set_transient( 'myprefix_instagram_data', $new_data, '10800' );
  
  	// Now let's set the variable $instagram_data to the new data we just got
  	$instagram_data = $new_data;
	
}


// Do the rest of your stuff here....