What does the computation do ? That is going to determine whether it is suitable for GPU conversion.
For gpu use, you would probably want to do something like
temp = permute(reshape(YourMatrix, [], size(YourMatrix,3)), [2 3 1]);
this rearranges you first 2 dimensions into a vector, the moves the third dimension to the first and the first to the third... giving you a 300 x 1 x 1400000 array. You can then pagefun() that to have each 300 x 1 treated as a group.
