How to improve the processing speed of RisingWave in Sink decoupling mode?

[artorias1024]

This is the statement I used to create the sink.

SET BACKGROUND_DDL = true;
set sink_rate_limit = 5000;
set streaming_parallelism_for_sink = 5;
SET sink_decouple = true;
CREATE SINK bicore.mamba_dwd_allocation_detail_adb_sink from bicore.mamba_dwd_allocation_order_detail_mv WITH (
    connector = 'jdbc',
    jdbc.url = 'jdbc:mysql://************',
    user = '************',
    password = '************',
    table.name = 'mv_allocation_order',
    type = 'upsert',
    primary_key = 'cid,detail_id'
);

I tried adjusting the sink_rate_limit and streaming_parallelism_for_sink parameters, but it doesn't seem to have a noticeable impact on the downstream MySQL; the write rate remains very uniform.

From my current understanding, when sink_decouple is enabled, data will be written into the Log Store? Essentially acting as a buffering queue?
So how can I increase the speed of consuming data from this queue?