Oracle stored procedure performance

Hi,

For below sp having a performance issue,if i am passing all parameter its work fine ,but when pass 2 or 3 parameter its goes to time out.expert plz look and provide to improve performance might be work on join."this sp is only checking duplicate records in DB"
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create or replace PROCEDURE SP_Duplicate

        (

        pi_meme_ssn                IN                INT,

        pi_meme_first_nm        IN                VARCHAR2,

        pi_meme_last_nm            IN                VARCHAR2,

        pi_meme_birth_dt        IN                DATE,

        pi_meme_city            IN                VARCHAR2,

        pi_meme_state            IN                VARCHAR2,

        pi_sbad_zip_cd            IN                VARCHAR2,

        pi_grgrck_no            IN                INT,

        po_return_value            OUT                VARCHAR2

        )

 

IS

 

vl_total_cnt    INT;

 

BEGIN

/* On the basis of the input parameters validation of DUPCHK process is done */

    IF    pi_meme_ssn        =    0

        AND    pi_meme_first_nm    IS    NULL

        AND    pi_meme_last_nm        IS    NULL

        AND    pi_meme_birth_dt    IS    NULL

        AND    pi_meme_city        IS    NULL

        AND    pi_meme_state        IS    NULL

        AND    pi_sbad_zip_cd        IS    NULL

        AND    pi_grgrck_no    =    0        THEN

 

        po_return_value :='N';

 

    ELSE

 

        SELECT    COUNT(1)

        INTO    vl_total_cnt

        FROM    cmc_meme_member meme,

                cmc_mepe_prcs_elig mepe,

                cmc_sbad_addr sbad

        WHERE    meme.meme_ck                =        mepe.meme_ck

        AND        mepe.mepe_elig_ind            =    'Y'

        --AND    SYSDATE BETWEEN mepe.MEPE_EFF_DT AND mepe.MEPE_TERM_DT

        AND        meme.meme_ssn                =        NVL(DECODE(pi_meme_ssn,0,NULL,pi_meme_ssn),meme.meme_ssn)

        AND        LOWER(meme.meme_first_name)    =        NVL(LOWER(pi_meme_first_nm),LOWER(meme.meme_first_name))

        AND        LOWER(meme.meme_last_name)    =        NVL(LOWER(pi_meme_last_nm),LOWER(meme.meme_last_name))

        AND        meme.meme_birth_dt            =        NVL(decode(pi_meme_birth_dt,'',NULL,pi_meme_birth_dt),meme.meme_birth_dt)

        AND        meme.grgr_ck                =        NVL(DECODE(pi_grgrck_no,0,NULL,pi_grgrck_no),meme.grgr_ck)

        AND        LOWER(sbad.sbad_city)        =        NVL(LOWER(pi_meme_city),LOWER(sbad.sbad_city))

        AND        LOWER(sbad.sbad_state)        =        NVL(LOWER(pi_meme_state),LOWER(sbad.sbad_state))

        AND        sbad.sbad_zip                =        NVL(pi_sbad_zip_cd,sbad.sbad_zip)

        AND        sbad.grgr_ck                =        meme.grgr_ck;

 

        /* If the count is greater than or equal to 1 then the output will be 'Y' that is duplicate */

        IF    vl_total_cnt    >=    1    THEN

 

            po_return_value :='Y';

 

        ELSE

 

        /* If the count is equal to 0 then the output will be 'N' that is  not a duplicate */

            po_return_value :='N';

           

        END IF;

 

    END IF;

END;