First, move the downscrollCam position calculation before the isOnScreen check to prevent culling errors.

Simplify the bloated downscrollCam calculation:

// Before:
final xx = x;
x += origin.x - offset.x;
x -= __strum.x; x *= -1; x += __strum.x;
x -= origin.x - offset.x;
x += __strum.width; // ??? maybe this isnt good

// After:
x = -x + 2 * (__strum.x - origin.x + offset.x) + __strum.width;

These are actually equivalent.

Additionally, implement caching for extensive arrow calculations. If the calculation for an arrow remains unchanged from the previous one, reuse the previous result. This significantly reduces computation. For example, __noteAngle previously required a separate calculation for each arrow. After this change, if all arrows in the list are the same, it will only be calculated once.

Remove abs from scrollSpeed. Since there's no need to ensure correctness during runtime, if users find errors related to this, they can correct them in their own large codebases. Some may even intentionally want that "incorrect" effect.

Remove the setter in the calculations within updateSustainClip and set_clipRect, keeping only the values that are actually needed from the original setter.

Finally, removed the unused static variable __notePosFrameOffset. Changed the static variable __posPoint to a local variable, making the code cleaner and improving performance.