The current EVM processes smart contracts sequentially due to its stack-based interpreter architecture, and frankly, this design comes with real overhead. The interpreter spends considerable resources managing the stack data structure itself—pushing, popping, managing memory—rather than doing the actual computation work.

Here's a practical way to visualize it: imagine a cafeteria plate stack. Each time you need a plate, you must remove it from the top. If you're building a meal setup with multiple ingredients, you're constantly stacking and unstacking plates just to access what you need. The more complex your operation, the more time goes into managing the stack rather than preparing the food. That's essentially what happens with the EVM—the overhead of maintaining the stack grows, and execution efficiency suffers. This architectural constraint has sparked ongoing discussions in the developer community about optimization possibilities and potential future improvements to how the VM handles contract execution.