SignalR Handle Multiple Clients in my Scenario

I currently have multiple clients who need to be informed when a customer creates a new order. Each customer is registered to an individual client and customers create orders on my website (each order has a particular client id when created).

I’m currently using polling and each client hits my API every few seconds and gets a list of new items. This is not ideal to say the least! I would like to find a way of finding a more efficient way.

Ideally each client should be pushed/sent each new order as they come in instead of the client continually hitting my server every few seconds. Is this possible with signalR or some other technology?

If it is would signalR be able to wait for a new order then push that order straight out to the client then store the order in the database? Or would signalR be watching the database table and then retrieve a list of new orders? Would this put a load on the DB?

Any ideas would be appreciated.