For memory constraint systems, one may run using a smaller size for chunk_size. In this case 4 MB will do just fine. For this demonstration, a smaller chunk size value decreases the wait time for workers to read again. It completes in 0.476 seconds for 26.4 x performance increase.

chunk_size => '4m',
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The slurped example is likely fast enough. Parallel is nice if you want that. But, serial doesn't take that long either. All completed in less than 20 seconds.