at first, never let users to backspace for update,insert and delete transactions. Ajax is the best way to increase speed of website but you should know where to use it. if you dont want to refresh same page use ajax. but if you need to refresh page content all over, dont use ajax. especial if you use so many queries in a web page, try to use ajax to minimize it. Ajax is just to decrease client server traffic, not to control backspace so use it where you have so much traffic.