Please advice what might be wrong so that database writing really slow

DATABASE PAGE SIZE = 1024

Here is details of my table containing BLOB field
I use IbExpert to view the table sctructures

I am trying to write master details record
One header record might contain 5 detail records or more

Master record:
=============
Total numbers of fields in the table = 28 column
Total record length = > 437
Numbers of Blob field in the record = 1 column
Blob size = 80 subtype = binary

RQ_DOC_NO VARCHAR(10) CHARACTER SET NONE NOT NULL,
USER_NAME VARCHAR(31) CHARACTER SET NONE NOT NULL,
CUST_CODE VARCHAR(10) CHARACTER SET NONE,
CURR_CODE "DomVChar3" /* "DomVChar3" = VARCHAR(3) */,
RQ_REF_NO VARCHAR(30) CHARACTER SET NONE,
RQ_DATE DATE,
RQ_CLOSING_DATE DATE,
RQ_PRIORITY VARCHAR(15) CHARACTER SET NONE,
RQ_REQUESTOR_NAME VARCHAR(30) CHARACTER SET NONE,
RQ_POSSIBILITY DECIMAL(3,0),
RQ_FOLLOWUP_DATE DATE,
RQ_DATE_CREATED "DomDate" /* "DomDate" = DATE */,
RQ_DELIVERY_TIME "DomVChar50" /* "DomVChar50" = VARCHAR(50) */,
RQ_DLV_DAYWEEK VARCHAR(1) CHARACTER SET NONE,
RQ_DOWN_PAYMENT NUMERIC(6,2),
RQ_PAYMENT_TERM "DomVChar30" /* "DomVChar30" = VARCHAR(30) */,
RQ_SHIPMENT_CHARGE NUMERIC(11,2),
RQ_BANK_CHARGE NUMERIC(9,2),
RQ_PACK_HANDLE NUMERIC(9,2),
RQ_EST_WEIGHT NUMERIC(8,2),
RQ_VAT_CLAUSE NUMERIC(1,0),
RQ_DLV_TERM "DomVChar50" /* "DomVChar50" = VARCHAR(50) */,
RQ_VALID_UNTIL "DomDate" /* "DomDate" = DATE */,
RS_STATUS "DomVChar10" /* "DomVChar10" = VARCHAR(10) */,
RQ_DISC_PRINTED SMALLINT,
RQ_FOOTNOTE BLOB SUB_TYPE 0 SEGMENT SIZE 80,
RQ_DATE_YEAR COMPUTED BY (EXTRACT(YEAR FROM RQ_DATE)),
RQ_DATE_MONTH COMPUTED BY (EXTRACT (MONTH FROM RQ_DATE))

Details record:
================
Total numbers of fields in the table = 15 column
Total record length = 407
Numbers of Blob field in the record = 2 column
Blob size = 80 subtype = binary

RQ_DOC_NO VARCHAR(10) CHARACTER SET NONE NOT NULL,
RD_ITEM_CODE "DomVChar50" NOT NULL /* "DomVChar50" = VARCHAR(50) */,
RD_ITEM_DESC BLOB SUB_TYPE 0 SEGMENT SIZE 80,
RD_REF_NO "DomVChar30" /* "DomVChar30" = VARCHAR(30) */,
RD_QTY DECIMAL(9,2),
RD_PRICE "DomNum152" /* "DomNum152" = NUMERIC(15,2) */,
RD_DISC_RATE "DomNum132" /* "DomNum132" = NUMERIC(13,2) */,
RD_DISCOUNT "DomNum152" /* "DomNum152" = NUMERIC(15,2) */,
RD_NETTO "DomNum152" /* "DomNum152" = NUMERIC(15,2) */,
RD_SUBTOTAL "DomNum152" /* "DomNum152" = NUMERIC(15,2) */,
RD_SUBTOTAL_USD "DomNum152" /* "DomNum152" = NUMERIC(15,2) */,
RS_STATUS "DomVChar10" NOT NULL /* "DomVChar10" = VARCHAR(10) */,
RD_REMARK "DomVChar40" /* "DomVChar40" = VARCHAR(40) */,
RD_INTERN_RMK BLOB SUB_TYPE 0 SEGMENT SIZE 80,
FH_DOC_NO "DomVChar10" /* "DomVChar10" = VARCHAR(10) */




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