Efficiently cut sentences in PHP using RegEx

separateSentences.php

<?php
  separateSentences($text) {

        $split_sentences = '%(?#!php/i split_sentences Rev:20160820_1800)
    # Split sentences on whitespace between them.
    # See: http://stackoverflow.com/a/5844564/433790
    (?<=          # Sentence split location preceded by
      [.!?]       # either an end of sentence punct,
    | [.!?][\'"]  # or end of sentence punct and quote.
    )             # End positive lookbehind.
    (?<!          # But don\'t split after these:
      Mr\.        # Either "Mr."
    | Mrs\.       # Or "Mrs."
    | Ms\.        # Or "Ms."
    | Jr\.        # Or "Jr."
    | Dr\.        # Or "Dr."
    | Prof\.      # Or "Prof."
    | Sr\.        # Or "Sr."
    | T\.V\.A\.   # Or "T.V.A."
    )             # End negative lookbehind.
    \s+           # Split on whitespace between sentences,
    (?=\S)        # (but not at end of string).
    %xi';  // End $split_sentences.

        $sentences = preg_split($split_sentences, $text, -1, PREG_SPLIT_NO_EMPTY);
        foreach ($sentences as $key => $sentence) {
            if(!preg_match("/ [a-zA-Z09]{1}(?=\.)/", $sentence)) {
                if($key > 0) {
                    $sentences[$key-1] = trim($sentences[$key-1] . ' ' . $sentence, ' ');
                    $sentences[$key] = null;
                }
            }
        }

        $sentences = array_filter($sentences);

        return $sentences;
    }
?>