I am facing the same issue with this library.
Why are you using that library? The ethernet library included with the IDE works good. What do you think you are getting with that library that is better than the standard library?
Because i simply want to get some LEDs blinking during a server call which isn't possible with the standard Ethernet library due to the blocking behavior of all its methods.
That is not true. The OP admits that is the first response.
Yep sorry you're right, actually client.print and write aren't blocking.
I was more thinking about connect() and begin() methods.
The connect() and begin() functions aren't blocking either. The DHCP begin() call is "blocking" if you have a SD card in the slot and don't disable or initialize it. Then the Ethernet.begin(mac) call will never return.