Can anyone make this sql query faster

SELECT
    c.id as CID,
    c.name as name,
    (
        SELECT (CASE  WHEN c.enabled = 0 THEN 'Disabled' ELSE 'Enabled' END )
     ) AS enabled,
    (
        SELECT
            coalesce(sum(ii.total),  0) AS total
        FROM
            si_invoice_items ii INNER JOIN
            si_invoices iv ON (iv.id = ii.invoice_id)
         WHERE
        iv.customer_id  = CID 
    ) as customer_total,
    (
        SELECT
            coalesce(sum(ap.ac_amount), 0) AS amount
        FROM
            si_payment ap INNER JOIN
            si_invoices iv ON (iv.id = ap.ac_inv_id)
         WHERE
            iv.customer_id = CID
    ) AS paid,
    ( 
        select customer_total - paid 
    ) AS owing
FROM
    si_customers c
WHERE 
    c.domain_id = '1'
ORDER BY
     name asc;