In my opinion, the answer highly depends on your architecture. If you have several small services for different kind of things, then you might go for multiple API calls. However, what's one of the most important goals of web development today? UX. You should try to develop an approach which is fast; and if both are fast, use the approach which fits your architecture better. Hence, you might consider one call, which contains everything, if all five calls finish quickly. Serializing objects does not take as much time as some may think, and multiple API calls always include HTTP overhead, which in general is a lot more expensive than a call to JSON.stringify() .
So, to put it in a nutshell, do both and do benchmarks. Then decide for either based on facts, not on our advice and speculation.