Check your internet connections 

Most probably this is the core reason behind the message delaying issue, so once again make confirm that your internet connection is working properly. You can verify the same in internet service provider page, the same delaying issue will happen when the receiving message size is too large in respect to the internet speed. Also the delaying in internet connection happening when the application is not properly configured or the device is not compactable.  You can also verify the same to Yahoo technical support; contact them on today if you needed.