The main factor to consider is that you are currently in year 11. This means that none of your results in year 11 will count towards your HSC results/ATAR. Year 11 constitutes a good opportunity for you to determine the best subject combination to maintain as you start year 12, which is done by experiencing a range of subjects. Year 11 also provides an opportunity to develop and improve a study strategy that suits your subjects and which would enable you to achieve favourable results, which becomes increasingly important in year 12. Based on this, perhaps you could keep English Extension 1 instead of making a premature decision that may not be as well informed as if you take your time to experience the subject throughout year 11. By then, you may still end up finding that you wish to drop this subject. However, if that is the case, you will have ensured that your decision would be well-informed and that you would not regret dropping it.
Another element that may be relevant to you is whether you are interested in taking Mathematics Extension 2 in year 12. If this applies, and assuming that your school sets a minimum performance standard for students wishing to take Mathematics Extension 2, you will likely need to prioritise Mathematics Advanced and Mathematics Extension 1 throughout year 11, even if that might impact your performance in your other subjects which is not problematic in year 11. Here, you should consider whether keeping English Extension 1 would result in an unnecessarily overwhelming workload (since you mentioned the length of your assessment tasks) that might hinder your progress towards taking Mathematics Extension 2.
I hope this helps!
