Storage Packing

Storage packing is a technique used in smart contract development to optimize gas consumption by fitting multiple smaller variables into a single 32-byte storage slot. The Ethereum Virtual Machine stores data in 256-bit slots, and if a variable occupies less space, the remaining bits are often wasted.

By carefully ordering variables in a contract, developers can combine several data points into one slot, thereby reducing the number of costly storage write operations. This is particularly effective for variables like booleans, timestamps, or small integers.

When data is packed, the contract reads or writes the entire slot at once, which is more efficient than accessing multiple individual slots. This practice is fundamental in creating cost-effective margin engines and accounting systems.

It requires precise planning during the contract architecture phase. Improper ordering can lead to higher gas costs, so developers must be mindful of the slot layout.

It is a critical skill for optimizing the performance of high-frequency trading protocols.