php - How to debug bad performance on code igniter 3 + sql_server 2008 -

on project developed code igniter 3.0.1 accessing sql_server 2008 database bad response times when using 'real' database. (>5 seconds serving page).

the same project tested in several test environements works fine, 'normal' output times (<1 second).

so imagine there's performance issue real database. none other db applications seem have perfomance problems. real db admin says 'everything fine our database. no 1 else has problem.'

i'm stucked. don't know else try.

how can debug find out performance issue is? or hint appreciated.

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detailed versions of tools , environements used:

real environment: web server: xampp 5.5.30 on windows 7. database server: sql_server 2008 on windows server 2008 r2 standard.

several test environements: web server: same xampp 5.5.30 on windows 7 , windows 10. tested older xampp versions. database server: sql_server 2008 express , sql_server 2014 express. on windows 7 , windows 8.

network: tested both in same computer xampp , in diferent computers. tested in same network real environement , tested in other networks.

db driver: using native drivers connect sql_server:

$db['my_db_name'] = array(     'dsn'    => '',     'hostname' => 'my_server\sqlexpress',     'username' => 'xxx',     'password' => 'yyy',     'database' => 'zzz',     'dbdriver' => 'sqlsrv',     'dbprefix' => '',     'pconnect' => false,     'db_debug' => true,     'cache_on' => false,     'cachedir' => 'application/cache',     'char_set' => 'utf8',     'dbcollat' => 'utf8_general_ci',     'swap_pre' => '',     'autoinit' => true,     'encrypt' => false,     'compress' => false,     'stricton' => false,     'failover' => array(),     'save_queries' => true ); 

there's few ways start looking locally:

• install profiler (xdebug functions 2-in-1 this) , use cache grind viewer (phpstorm supports there's other tools out there) see bottlenecks
• use apm newrelic drill down different calls , queries (i don't know if profilers xdebug or xhprof go deep queries)
• ensure database indexed , structured (this seems me since issue on database calls)