Dear client,
First of all I want to mention that there is no Angular version of 3, it was skipped and after 2nd version the 4th was released. Anyway, I can suggest strategies, by which I can optimize the load time for your angular project, first of all we can update the version to the latest, secondly we can divide the code into modules and make the app run with lazy loading, it will improve the startup load time, thirdly we can review the components and remove unused code or make it more optimal. Besides that if the API is in node.js we can compress the contents of requests and do some optimizations there. If you are interested, we can discuss more details on the project.
Best,
Davit