Relay node delays

[afulki]

I have a serial gateway (Arduino Uno) and two sensor nodes (Arduino Nano 5v), one reporting temperature (working great) and one with a relay board and 4 relays attached, while the board is working I'm seeing delays of 2s to 3os before the relay is activated.

On the serial monitor attached to the relay control nano , I see the incoming message almost immediately, but not the ack (or what I assume is the ack as I'm new to this).

Incoming change for sensor:2, New status: 0
read: 1-1-0 s=0,c=1,t=0,pt=7,l=5,sg=0:17.9
read: 0-0-2 s=3,c=1,t=2,pt=0,l=1,sg=0:1
send: 2-2-0-0 s=3,c=1,t=2,pt=0,l=1,sg=0,st=ok:1

Sometimes I see the read, but no ack and no change on the relay control pin:

Incoming change for sensor:3, New status: 1
read: 1-1-0 s=0,c=1,t=0,pt=7,l=5,sg=0:18.0

Any help would be appreciated.