First of all, I'd like to note that request-reply communication pattern is much slower than pub-sub, and this is true not only for ROS, but for other communication frameworks like 0mq and AKKA. ROS services implement the request-reply pattern so avoid them when high performance is important.

Maybe you could use the jog_arm package as mentioned in this answer but I haven't tried this solution myself.

For my current real-time teleoperation framework I use a custom implementation of inverse and forward kinematics solution simply following the tutorial from MoveIt. The node subscribes to a cartesian pose topic and publishes corresponding joint states, and subscribes to a joint states topic and publishes cartesian poses. This way I can run the control loop at 1KHz, and it can work even faster, if necessary.

So I recommend you to get your hands dirty, write a little bit of code, and you'll be able to implement more sophisticated things like converting cartesian velocities to joint speeds, which is crucial for teleoperation or visual servoing of manipulators like UR5.