AWS Lambda lifecycle and in-memory caching
TJ Holowaychuk

One thing to consider is that as your concurrency grows, the hit rate will decrease, as the data may not exist in that particular container, so you will have to consider this in your use-case.

In other words, this is perfect for caching low cardinality data. For high cardinality and high concurrency this might decrease performance, because of LRU overhead and high cache eviction rates.