So I've been experimenting with different processes for memorising, and reading a little about the process.
Essentially (and no doubt highly simplified) when you read the brain process is different to that of when you play from memory - the signals fired between neurons are actually different. Thus in order for me to memorise faster I must immediately start playing from memory, not reading through repeatedly. I knew this already but it seems I wasnt really acting on it.
So the initial test process was as follows, away from the instrument - read half a bar of the middle voice (not the bass note or the melody) once. Immediately attempt to recall the names of the notes from memory. Regardless of whether I successfully recalled the notes, read the half bar again, the recall it, twice. Read again - recall 3-4 times. This was enough for me to then look at keyboard memory, I knew what the notes were so now I could focus on how to play them. I visualised the notes on the keyboard and imagined how it would feel to play them. I repeated the process of read/recall/read/recall until I could comfortably recall how to play the notes quickly and without the need to refer back to the score at all.
At this point I added in the bass/melody to the section and repeated the process again. Then did the whole thing for the next half of the bar, then put the whole bar together (all in my head). I worked through 4 bars like this and was sucessfully able to recall the whole thing in time with no mental stutters after about 15-20 minutes.
In theory that means I should be able to get through the whole piece in a touch over 2 hours. There's a problem though, 4 bars was enough to fatigue me mentally. But I think partially thats because the particular piece is perhaps harder to remember than others because the patterns within the notes are less discernable. Additionally, now that it is several hours since I did that I can no longer recall the passage without mental blocks.
-------------------
Another thing I attempted yesterday was to write out the score by hand - interesting. Turns out there was a mountain of information on the score that I thought I had taken in and yet a just hadnt. For example, I started by trying to write down as much as I could without having to refer to the score first which turned out to be very little, I actually didnt even know what the time signature was - I couldve used some thinking/ear skills to figure a fair bit out but that was not the point of the exercise so I just worked on memory.
Anyway, I also plan to write out several different versions of the score - one that is bass/melody (structural outline), one that it the middle voice (connectivity between structural points), and one that is the whole thing (memorising the whole unit together).. which will no doubt take me a very long time, but I suspect that I will speed up as it goes on and when i try it again on a new piece.
------
also pushed to play through the middle E major section last night, not too challenging - will be looking at the return to Eb minor tonight.