We know that WordPress is a great blogging platform, using by many geek and techies. In this platform Post revisions one of good feature, so you can revert to previous changes at anytime. Generally WordPress stores your post updates as revisions. The many numbers of post revisions cause increase your database sizes thus making site load time high. By deleting every post revisions you can Slightly improve site performance.
Remove post revisions
Install and activate a plugin called wp optimize if you have not already get it from WordPress store by dashboard >> plugins >>add new or download from Wordpress.org and upload to your site. After you have activated this plugin see for wp optimize setting on your dashboard. You can not delete the post revisions by using this plugin, additionally can remove auto draft post, remove unapproved comments, remove ping backs and track backs spam comments, optimize database. Go clean up options you can see many options in it you must tick that clear all post revisions you can also tick another options if you need then click on process. To automatically delete post revisions go to settings tab under auto clean up settings.