Hi,
If your ops are small (and I assume they are since you don’t batch), the overhead of multiprocessing is most likely going to be much higher than any benefit you’re gonna get from it 
The best thing to do here woukd be to change L to accept batch of inputs (don’t hesitate to ask questions about this here).
Otherwise, the for-loop will be the best thing you can do. Maybe multithreading can be a bit faster but will make your code much more complicated.