To determine if you are connected to RTO or not - you can refer to the 3 Websocket API QuickStart sections and compare your credentials/connectivity parameters and service name with the ones used in the 3 different Quick Starts.
So, say you are consuming data from a service call ELEKTRON_DD and providing a MachineID + password + clientID/AppKey - then you are using RTO.
RTO is already using conflation / Bandwidth optimisation to limit the number of updates to 3 + Trades (as generally speaking most customers do not wish to miss Trade activity).
If you are connecting to your organisation's ADS then you won't be providing a password. If you are using an ADS you need to discuss conflation with your own internal MarketData team.
In terms of how many updates Websocket connection can support - we recommend customers perform their own testing within their own environments with their own watchlist.
This is because the actual number of updates your application can handle can vary based on factors such as your network/internet connection, your watchlist size, the volatility of the instruments in your watchlist, the typical size of the updates, the language you are using, how much processing you do to the payload on the same thread that receives the payload etc. If your application consumes the data too slowly, the server will eventually disconnect you once its buffer (for your session) is filled.
In terms of maximum messages received per second, this can vary quite considerably depending on the volatility of your instruments, any conflation on the feed/service you are connecting to etc.
For example, if you are connecting to our Real-Time Optimised feed, this provides 3 Updates per second + any trades. So, you could get 3 or more updates per second per instrument - depending on how actively the instrument is being traded. If the instrument is not quoted or traded that often you may get less than 3 updates per second.
If you are connecting to an internal ADS server at your organisation, then you will need to check with your Market Data team to check if the service is conflated or not. If not conflated, you could far more than 3+ updates a second - depending on how actively the instrument is quoted + traded, as explained above.