Decrease add to cart button loading 10s to 1s

Job ID: 34851411

Budget: $250 – $750 USD

Hello, my problem is urgent, 24h maximum
I have a website under wordpress on which a php module has been implemented with a developer.
it allows the user to personalize his text with a google map
A bit like Mapiful.com
When the user has finished his customization, and presses add to cart, it automatically generates an image in the backend.

The problem is that the button takes about 6s - 10s and sometime more to go to checkout.
I want it's take not more than 2s
The developer did his best to reduce the time but he told me he can't anymore
Can you help me because it's very urgent
Related categories: PHP JavaScript WordPress HTML Google Maps API