It seems that the arraySlice() implementation works by iterating over the entire key-space in the array in order to locate the slice-offset. As the size of the target array increases, so does the performance cost of the arraySlice() call. This is strongly related to the location of the slice within the overall array.

By not using arraySlice(), I was able to improve the performance of my algorithm by 500x. I’m sure there is a reason that arraySlice() is written the way it is and it probably handles edge-cases that my code doesn’t actually have to worry about. But, I’m just letting you all know in case there is something worth re-evaluating.

Here’s my particular context - I was splitting a massive array up into smaller arrays for sub-processing: