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Compression, synchronization and backup systems often use rolling hash to implement "content-defined chunking", an effective form of deduplication.

In optimized implementations, Rabin-Karp is likely to be the bottleneck. See for instance https://github.com/facebook/zstd/pull/2483 which replaces a Rabin-Karp variant by a >2x faster Gear-Hashing.

I found it to be a good pedagogical tool. In terms of actual use cases, maybe something like rsync'ing a large directory where only a few files have changed? It starts to get pretty contrived though.

Maybe implementing `foo LIKE '%bar%'` in a columnar DB backed by SSDs. Even if you're not strictly CPU-bound, there's a scale where you might care about the power use.