API Response Time Takes Too Long

hello,

i'm developing website using php and using box as storage platform integration

because there's no SDK on php, i'm developing converting curl request via guzzle

everything is working fine i can do all api calls

i'm following docs , so everytime i make an api calls

it will have simplified flow like this

1. api call to get access token using JWT (API) https://developer.box.com/docs/construct-jwt-claim-manually

2.  After getting access token, doing api call  (https://developer.box.com/v2.0/reference)

as i mention before everyting is working fine, but it takes too long to load , 1 call can takes 2.2s- 2.8s, so basically 1 api call process (e.g : get thumbnail) , it will take at least 4.4s to load,

before that, i'm aware that i might have coded problems,

but i already tried using postman and try to direct call the url

it gave me the same response time that is between 2.2s - 2.8s

my question is : is it normal ?

*note : both on development environment and live server gave equal response time 4.4s at least to done an api calls

**note: still on free account, wanna get upgraded account but considering this problem.