By default WordPress auto saves post on every 60 seconds, but you can easily modify this time according to your like. Open your site’s wp-config.php file and add the following line just above the Happy Blogging line:
define(‘AUTOSAVE_INTERVAL’, 120); // in seconds
In the above line I have given time of 120 seconds, you may change that as per your requirement.
You can also modify post revisions by limiting the number of revisions per post:
define(‘WP_POST_REVISIONS’, 5);
And for disabling post revision, set it to false as shown below:
define(‘WP_POST_REVISIONS’, false);