Hello @JM_VFAU.
I would say the additional delay will depend on the latency between the server and the F5. Since SSL requires multiple back and forth iterations for the SSL handshake latency will play a siginificant role here. Usually, SSL handshake takes 4 legs in comparison to 2 legs for HTTP.
However, for the situation where you have F5 and RTDM in the local network impact should be minor and based on our experience enabling SSL will add somewhere around 15-20ms for the request.
Ivan Baranov, Tier One Analytics