How much computation time (blocking the event loop) is too much?



I have an app in which I have to sync large amounts of data with an external API. This data has to be formatted before I insert it into my own DB.

For example. I might get 100 documents in an API response, to which I currently loop over to ready the data. Using Kadira, I can see that this causes temporary blocking of the event loop (like 300ms spent on computation) for large API responses.

My question is, how much computation can I get away with before I run into problems, 10ms, 50ms, 500?

Also, if it turns out that my current solution won’t hold up, what is a good alternaive? a seperate service?