A good example is for a bloom filter: using sha256 is much too slow for good filter performance, you want something like siphash or some other non-cryptographic hash.

Here's a good story of the performance benefits of switching from cryptographic to non-crypto hashes: https://github.com/bitly/dablooms/pull/19

(But I don't recommend you use murmur anymore: https://emboss.github.io/blog/2012/12/14/breaking-murmur-has... (although tbh I could be wrong on this one, not an expert))

(Shameless plug for my bloom filter tutorial https://llimllib.github.io/bloomfilter-tutorial/ )