# When Bloom filters don't bloom

Modern CPUs are really good at sequential memory access, whet it’s possible to predict memory fetch patterns. Random memory access is very costly.

Modern computers require cache-optimized algorithms. When working with large datasets, not fitting L3 cache, prefer optimizing for reduced number loads, over optimizing the amount of memory used.

Bloom filters are great, as long as they fit into the L3 cache. They are optimized for memory usage, not memory access. A nice alternative is Cuckoo Filters.