> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ziplime.limex.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Under the Hood

> Performance and versioning inside the engine

## Performance

Calculations are accelerated using the **Polars** dataframe library, with select performance-critical components implemented in **Rust**. This keeps backtests fast even over long history windows and fine-grained (minute-level) data.

## Parameters and versioning

Strategy parameters can be defined separately from the strategy's logic, so they can be tuned — for optimization, for example — without touching the underlying code. Every change to a strategy's code is kept in version history, so a strategy is a project that evolves over time rather than a single frozen result.

## No restriction on strategy type

The engine doesn't constrain the kind of strategy you build. Portfolio strategies, pairs trading, momentum, or anything else — all run on the same underlying engine.

<Note>
  This page describes the engine's architecture at a conceptual level. For hands-on strategy examples and code, see [Writing Strategies](/language/writing-strategies/three-levels).
</Note>