Analysis of the TPC-H test results obtained in request #16. Volumes of 30 GB and 50 GB

Conducted testing of TPC-H with base volumes of 30 GB and 50 GB. For query # 16, the runtime results are very similar. At 50 GB, it seems that the execution time of a request is a few hundredths of a second even less than the execution time of 30 GB. How can this be explained?

Test run times IMG

The SQL query itself looks like this:

select
    p_brand,
    p_type,
    p_size,
    count(distinct ps_suppkey) as supplier_cnt
from
    partsupp,
    part
where
    p_partkey = ps_partkey
    and p_brand <> 'Brand#34'
    and p_type not like 'MEDIUM BRUSHED%'
    and p_size in (10, 18, 2, 41, 20, 15, 5, 7)
    and ps_suppkey not in (
        select
            s_suppkey
        from
            supplier
        where
            s_comment like '%Customer%Complaints%'
    )
group by
    p_brand,
    p_type,
    p_size
order by
    supplier_cnt desc,
    p_brand,
    p_type,
    p_size;
GO

Specification for a given test TPC-H: drive.google.com

How can you characterize this?