Proactive Message Delay in Client

This is a bit of an overlapping issue between Sdk / Composer / Client, however posting it here.

I have developed an handoff integration with Genesys that is built around a websocket that calls ContinueConversationAsync when a new message arrives from the agent :

private async Task SendActivity(string eventName, string text = null, object data = null)
{
    await DialogContext.Context.Adapter.ContinueConversationAsync(_claimsIdentity, _conversationReference, new BotCallbackHandler(async (turnContext, cancellationToken) =>
    {
        turnContext.Activity.Type = ActivityTypes.Event;
        turnContext.Activity.Name = eventName;
        turnContext.Activity.Text = text;
        turnContext.Activity.Value = data;
        await _callbackHandler(turnContext, cancellationToken);
    }), default);
}

This is then picked up in Composer and send to the user:

The speed at which the message arrives at the client (emulator in this scenario) is within a second. However before it is actually displayed another 6 seconds pass.

So in the screenshot below the yellow marked "ola" arrives almost instantaneously but 6 seconds pass before it is displayed in the chat itself.

What is causing this?