As Paul says, it may go through a junction box. What you need to check is that only the wire to the master comes out of that, and similarly at any other box it goes through.
If there is no other wire shooting off anywhere you do not have star wiring, but I would also be surprised if replacing the master would have any effect. Zarjaz may know the probability there.
Star wiring would cause a speed loss such as you have.
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