Speedup compared to what? You can’t compare it to doing it in software on the same machine. So, you need to pick a reference CPU.
Finding a somewhat comparable CPU would be challenging. It would need to run at around 48 MHz and have 16 bit integer addition. I think the fastest Z80 clone would be a candidate (https://en.wikipedia.org/wiki/Zilog_eZ80), but that’s a pipelined CPU. You may find that unfair.
If you don’t pick something comparable but just something cheap, given the 48MHz clock of this hardware and the limited amount of parallelism, it wouldn’t surprise me if the typical modern smartphone could do it faster, even without the use of a GPU.
Finding a somewhat comparable CPU would be challenging. It would need to run at around 48 MHz and have 16 bit integer addition. I think the fastest Z80 clone would be a candidate (https://en.wikipedia.org/wiki/Zilog_eZ80), but that’s a pipelined CPU. You may find that unfair.
If you don’t pick something comparable but just something cheap, given the 48MHz clock of this hardware and the limited amount of parallelism, it wouldn’t surprise me if the typical modern smartphone could do it faster, even without the use of a GPU.