Wordpress plugin update - php

Question

I need to implement update for my plugin which is not on wordpress repository.
What I need to know is difference between two filters:
'site_transient_update_plugins' and 'pre_set_site_transient_update_plugins'
I implemented one class for update with 'pre_set_site_transient_update_plugins' filter:
class WPAutoUpdate{
public $current_version;
public $update_path;
public $plugin_slug;
public $slug;
function __construct($current_version, $update_path, $plugin_slug){
$this->current_version = $current_version;
$this->update_path = $update_path;
$this->plugin_slug = $plugin_slug;
list ($t1, $t2) = explode('/', $plugin_slug);
$this->slug = str_replace('.php', '', $t2);
add_filter('pre_set_site_transient_update_plugins', array(&$this, 'check_update'));
}
public function check_update($transient){
if (empty($transient->checked)) {
return $transient;
}
$remote_version = $this->getRemote_version();
if (version_compare($this->current_version, $remote_version, '<')) {
$obj = new stdClass();
$obj->slug = $this->slug;
$obj->new_version = $remote_version;
$obj->url = $this->update_path;
$obj->package = $this->update_path;
$transient->response[$this->plugin_slug] = $obj;
}
return $transient;
}
public function getRemote_version(){
$request = wp_remote_post($this->update_path, array('body' => array('action' => 'version')));
if (!is_wp_error($request) || wp_remote_retrieve_response_code($request) === 200) {
return $request['body'];
}
return false;
}
}
An instance of this class will be created from the main file of plugin:
$pluginData = get_plugin_data(__FILE__);
$plugin_current_version = $pluginData['Version'];
$plugin_remote_path = 'https://mysite.com/myplugin';
$plugin_slug = plugin_basename(__FILE__);
new WPAutoUpdate ($plugin_current_version, $plugin_remote_path, $plugin_slug);
The only problem is when I use 'pre_set_site_transient_update_plugins' filter and when new version of plugin is available, when I visit plugin page for the first time there is no information about new version. And then when I refresh the page there will be update option and each next visit on plugin page there will be update option, just not for the first visit.
And when I use 'site_transient_update_plugins' filter update information will be shown for the first visit and all works fine. Just I am worried because filter 'pre_set_site_transient_update_plugins' will be called just twice and 'site_transient_update_plugins' will be called 11 times.
So if I use 'site_transient_update_plugins' all will works fine but my function on this hook, which contain wp_remote_post() function, will be called 11 times on each visit plugin page.
Is that smart to do, is that to much expensive operation. Does anyone has some advice.