Expert Shopify App Developer

I am looking a Shopify "Expert" app developer, please only who consider themselves expert and have build apps in past for shopify contact. We have a custom shipping service app build in shopify

Our flow is like this

1. we call our own system api from shopify
2. "our own system" api calls third party api's providers for example shippy-pro (where you can add your contract carriers), and there are multiple providers like easypost and eaship as well
3. each of those third party api link provider then call carriers api's (like FedEx, UPS, DHL)
4. then we get results and we apply after logic on them, like commission rate, discounts etc.
5. also in between we calculate boxes requirement based on purchased products (we have predefined boxes already)
5. on the this last step rates are returned to shopify

but this processing takes time and our shopify app does not work, but if we remove all third party api providers and keep only one and call single carrier then it works. Before apply for this project please include word CR in your proposal first line to be considered.

It seems like it timeout issue, if someone can help this that will be highly appreciated

Regards,
Kamran