The hsp part that I relate to is the social aspect of it. And/or the physiological processing aspect of the different sounds and energies coming from people. Normal people see only people in the room and tune out everything else. Highly sensitives / psychics / intuitives are absorbing another world or two full of information at the same time, like what people are really feeling about you, how their ego is drawing energy from you or giving to you, what the tone of voice indicates, why they are the way they are underneath, motives for saying something, what your reaction is to that, the reactions of others, the nuances of energies both bodily and psychic that are bouncing around the room and echoing in the cacophony of sounds, your own heartbeat and body reactions, the moment you feel yourself withdrawing into a frozen deer in the headlights response, feeling the urge to run outside to get away from the craziness of everyones egoic desires, the tightening of muscles, the worry about what you should say in response, the worry about hiding your real reactions or not reacting enough, the muffled sounds when they mix together, its like the focus goes on the combined energy of everything at once that at first are fine and quickly become too much.
But when it comes to actual work type multitasking, I'm quite good at it. In fact, I can drop one deep focus item to grab a phone call and answer an email simultaneously and bounce back to a deep task of accounting - as long as I've had my vitamin B complex and its the first 3 days of the week I'm super fast and staying on top of it. Towards day four and five, I'm burning out more and have to push everything away, my brain gets tired after dealing with too much. This is why distractions like a mini time out watching a tv show I like will bring me back, or a walk outside will. I thrive on distractions, because each time I switch, it gives me more energy to come back to the other one. If its something I don't like I get bored and can only handle a little at a time, so multi tasking kind of works well so I don't get so bored.
Building personal boundaries and communicating about what and when something can be done is vitally important. Teaching others about your boundaries and making them respect them is vital. TAKING your time or having days where you do nothing but purge is also helpful.