Relatively high memory use per contract instance

Creating 100000 smart contract instances from *the same* module, and whose states are simple integers leads the nodes to use around 1GB of memory.

Restarting decreases the memory use to about 700MB. Block state stays reasonably small, around 42MB.

This means around 7-10kB of additional RAM memory per trivial smart contract instance, which seems excessive, seeing that all contracts are created from the same module (whose size is around 13kB).

It would be useful to both understand where this is coming from, and hopefully reduce the overhead, especially since it persists after restart.

I do not think this is high priority, but I wanted to record the data and observations.