Besides the CCU limit in Photon which you can easily increase by paying more there is a messages/second per room limit in Photon Realtime.
Dunno about latency, but the official Photon limit is 500 messages/second per room.
Let's say s
is your sendrate (s
messages per second) and n
is the maximum number of players allowed in a room.
So it's 500 = s * n^2
if you do the easy synchronization where every player sends their position etc. to all the other players. Photon counts that as:
1
sent message + n-1
received messages = n
messages.
This results in n = 7
for a sendrate s = 10
.