When you build the array of pictures you do it using auto-indexing out of a while loop. That means that memory is aquired for a copy of the previous picture array and the array is rebuilt on every iteration, this is slow and requires a lot of extra memory.
If you want to speed things up try initializing a shift register with a 3D array of a size that will be able to hold a certain number of pictures, then replace the "pages" as new pictures are aquired, replace operations do not require copying of the previous array and will thus be much much faster. The difference is exeptional when dealing with large arrays/amounts of data.
Now, the shift register buffer could be built into a functional global, and you can add a push/pop logic to it so that you can have a p
arrallell loop that works on writing the elements to disk. You could use a que for this, but I think even though you specify a size limit to the que it still aquires memory as new elements are added (correct me if I'm wrong people...:-)), so a functional global acting as a circular buffer og fixed size frame for a que should be better.
