There could be a performance improvement if hashing algorithms like MD5, SHA1, or SHA256 are being used by switching to xxhash64.
Could be a win for processing large directories with thousands of files or detecting whether a file has been processed before even if it has been renamed, because the hash of the contents would be the same. The process is the same as with current hashing algorithms, but xxhash64 is optimized for performance and for testing if file A is the same as file B, not whether file A has changed after some operation like decompression or decryption.
It is also useful in creating cache key-value pairs because of its compact memory use (64-bit hashes)