Drupal

Drupal 8 is shaping up to be another Drupal 7 waterfall without the benefits.

Open source lets anybody contribute to any code but it does nothing to ensure the contributor understands either the code they are contributing to or the code they contribute. Some open source projects add automated testing of code execution or code format. There is no tests for good design or applicability. The larger projects are crashing into problems created from accumulated contributions that misdirect people and the projects.

node_load_from_title() is a function for Drupal 7 to replace functionality lost in the changeover from Drupal 6.

Drupal offers some choices between performance and flexibility. There are heaps of recommendations for increasing performance and they are almost always applicable only to high volume Web sites where you have good control over the server and you have a very small proportion of your visitors logged in. Everyone else has to fight for performance from the ground up through the Web design and coding. Here are the critical design decisions.

The Drupal function drupal_lookup_path() is the biggest database access time consuming function on many Web pages and chews up ten times more than most other functions. There are some straight forward solutions and some difficult ones. Here are the problems and potential solutions. You can use the results in other database access code.

Notice: Undefined index: to in DefaultMailSystem->mail() (line 83 of /var/www/example.com/public_html/modules/system/system.mail.inc).

You forgot the $message['to'] part of $message.

You could be using a main function direct, mail($message);, or the following drupal_mail function with an invalid $to. An invalid $to is unlikely because processing will almost always stop with an earlier error message.
drupal_mail($module, $key, $to, $language, $params, $from, $send)

Warning: implode(): Invalid arguments passed in DefaultMailSystem->format() (line 23 of /var/www/example.com/public_html/modules/system/system.mail.inc).
Somebody broke the following line of code. You are sending mail without the body component or with the body component in the wrong place or with the body containing a string instead of an array.
$message['body'] = implode("\n\n", $message['body']);