Currently, in Splink, comparison functions (e.g., cosine_sim) are evaluated multiple times within CASE statements during the predict() process. For example:

CASE
    WHEN cosine_sim(l, r) > 0.9 THEN 1
    WHEN cosine_sim(l, r) > 0.8 THEN 2
    WHEN cosine_sim(l, r) > 0.7 THEN 3
    ...
END

This results in repeated computation of cosine_sim(l, r) for each threshold, which impacts performance.

Proposed Enhancement:

Where functions are being repeated computed, automatically refactor the logic to precompute the comparison value once and reuse it in the CASE statement. For example:

WITH precomputed_cosine AS (
    SELECT cosine_sim(l, r) AS precompute_cosine_value, ...
)
SELECT
    CASE
        WHEN precompute_cosine_value > 0.9 THEN 1
        WHEN precompute_cosine_value > 0.8 THEN 2
        WHEN precompute_cosine_value > 0.7 THEN 3
        ...
    END

This would makes it easier to use more granular thresholds without additional overhead - and allow users to more easily approximate match weights being a linear function rather than bucketed (by simply using a large number of thresholds)