The code in socket_connect will only call __socket_nodelay if priv->nodelay *and* priv->lowlat are both set.  Leaving aside the case where priv->lowlat is set because transport.socket.lowlat was set in client-protocol:init, the way both of these values are set in socket_init can yield some unexpected results.

In the case of lowlat, the value will be set based purely on the *presence* of transport.socket.lowlat, regardless of its value.  Thus, even if a user has "option transport.socket.lowlat off" in their config, priv->lowlat will be set.

More seriously, a comment in the code to handle transport.socket.nodelay says "By default, we enable NODELAY" but that's not true.  If the option is *not provided* then we never get into that block and priv->nodelay remains zero.  This causes the later check in socket_connect to fail, so by default we do not set TCP_NODELAY on any client sockets at all.  I've verified this in running code, with breakpoints in socket_connect.

The fix to the latter problem is simple: move the initialization of priv->nodelay to be above the dict_get block, instead of within it.