I have a PHP script which meets heavy load. It is a backend script for my smartphone game. In this script I do multiple inserts and selects with MySQL.
A) I was wondering if Stored Procedures could improve response and execution time?
B) Can I gain anything switching from MySQL to MySQLi in regards to response time? Or should I look for a completely different solution
Stored procedures would move the complicated logic to the database part of your system, so you would effectively leverage work (and maybe a lot) by avoiding PHP from issuing a lot of inserts. If something that you do server-script-side can be ported to a stored procedure, it is likely to improve performance.
For the second question, you should move from mysql API to mysqli API since the mysql API is already deprecated.
I am wondering if Stored Procedures can do anything for me with response time and quick executing?
No.
Can I gain anything going from mysql to mysqli in regards to response time?
No.
or should I look in a another direction?
It is impossible to show you whatever direction knowing nothing of your particular situation.
As a general rule, multiple inserts can be optimized by removing indexes. Batch inserts can be possibly optimized by using transactions.