Optimize for single capture case

[Erarndt]

Fixes #

Context

In most cases, an expression will only have one capture. We can optimize for that case and avoid allocating a size 4 array (list default) just to hold one element.

Before:

After:

This saves ~150MB

Changes Made

Testing

Notes

[Copilot]

Pull Request Overview

This PR optimizes memory allocation for expression captures by specifying an initial capacity of 1 when creating List instances, based on the observation that most expressions contain only a single capture. This avoids the default capacity of 4, reducing memory overhead.

Key changes:

• Modified List constructor calls to specify initial capacity of 1 for transformExpressions
• Added performance comments explaining the optimization rationale