The Statistics tab of the Preview Design window gives you statistics about the preview: number of props, groups, pixels, channels, etc. Of particular importance is the last section, which shows the number of channels assigned to each LOR network. This can help identify if a network is overloaded with too many channels. What constitutes "too many channels" will vary with network speed and the number of effects being sent to to the network.
This is the fifth of 5 tabs on the Preview Design window. The others are:
•Channel Conflicts & Bulk Changes
The Statistics tab
You can use the copy button 
to copy the displayed information to the clipboard so that it can be pasted into other applications.