The load may be heavy because of project state.
However, unless a replacement is found, you will be expected to bear it.
Once your replacement comes in, then you may offload a part of work to him/her, however the responsibility still lies with you unless your replacement is trained.
You are being paid full salary on notice period.
Then organization should also get full output.
Not working/ expecting a light workload just because you are in notice period is, in my personal opinion, unprofessional.
As long as you are on board the organization, you should give it your best, irrespective of if it's your first day or last day.
The world is a small place.
If you don't work well in your notice period, people will notice.
This can harm your chances of coming back to the organization in the future.
And who knows, someone senior or from HR from this organization may change to some other place where you are interviewing in the future.
A good reference can be lost by trying not to give 100% during notice period.
Since you have been promoted, sounds like you have spent sometime in the organization.
Would you like to give up all the good will you have earned just because you have some extra work during notice period?
workplace.stackexchange.com/users/74758/Rishi Goel
Is it normal to have heavy work load during notice period?
In my experience when someone is taking a new position and working their notice, it is not un-common for the current team to get as much productivity from the person as possible.
Since you are leaving the company, there is no reason for you to work yourself to death as you are moving on.
Do your best while you are there, but there is no need for you at this point to work extra hours or extra hard .
workplace.stackexchange.com/users/61096/Neo
There is no definitive "right" answer - it's totally dependent on the individual circumstances at the time.
I've known people that have had essentially nothing to do during their notice periods whereas my last three have all had me working flat out (and beyond) until almost the very end due to project state and the need to hand things over.
At my last perm role I was flat out until <30 mins before I was due to leave - I was even late to my own leaving presentation as a result!
As Rishi talks about in his answer
there's plenty of good reasons to stay professional and keep on working away during a notice period and to be honest
it's not that onerous to do so.
workplace.stackexchange.com/users/64903/motosubatsu
It's not uncommon, but the reasons vary.
Clearing the deck:
A mad rush to get everything done to give themselves some space to get the next person in Wrapping things up:
Make sure that everything you're involved in is finished Punative: Some companies DO get offended and will make you work to the very last second:
Business as usual Some companies just continue on until you're replaced.
It could be any one, a combination of, or none of the above, but a heavy workload on the way out is not unheard of.
workplace.stackexchange.com/users/46894/Old_Lamplighter
It is not so strange if you had an important role that the company wants to make sure they are ready to handle that you are not there when you have moved on.
Therefore try and interpret it as a compliment and not as a punishment.
workplace.stackexchange.com/users/45138/mathreadler
I am in a management role, where I have accepted a new role at a new company and serving my notice period. The work-load is very heavy which can be stressful and high-pressured. I am quite unsettled right now, changing roles etc and subsequently losing motivation.  In my last role (non management - developer), this was not the case, the work load gradually decreased over the course of the notice period. Is piling on the work once someone is leaving normal practice?
Is it normal to have heavy work load during notice period?
workplace.stackexchange.com
<notice-period>
workplace.stackexchange.com/questions/99396
workplace.stackexchange.com/users/40609/bobo2000
This is not uncommon. The company wants to get as much productivity from you as they can and be ready to handle your absence. The answer to this question is subjective and will depend on different factors. However, many people would not see this as strange since the company may well want to get as much productivity out of the employee before they leave.
The answer to this question will be subjective and depend on numerous factors. It is not generally considered uncommon as most businesses will want to get as much productivity out of an employee as they can before they leave.