Next are some tips for writing highly efficient PHP codes. They are described below:0. Use single quote to replace double quote, this will be better since PHP will serach for variables in double quoted strings. Note, only echo can do this;1. If we can define methods of a class as static, then do it. It will increase access speed by 4 times;2. $row["id"] is 7 times faster than $row[id];3. echo is faster than print, and also use echo's multiple parameter format such as echo $str1,$str2 instead of echo $str1.$str2;4. When using for loop, make sure the maximum number of executions instead of calcu...