Performance issue in Insert Select(Sybase)

Hi members,

I have a sp with number of Insert-select which is increasing the execution time of the sp. The approximate no. of records in the tables is around 10 million. Please suggest me the better way to improve the performance of following query. Please let me know either insert-select will be faster or select * into t2 from t1 will be faster.

insert #cr2_bondtemp
select
isnull(secId, 0) secId, ID_CUSIP, ID_SEDOL1, ID_ISIN, SECURITY_PRICE, null, BASIC_SPREAD, ISSUER, SECURITY_DES,
upper(MARKET_SECTOR_DES) + 'BOND',
case when CPN_TYP = 'DEFAULTED' then 'D'
when RTG_MOODY = 'N.A.' then 'NA'
else RTG_MOODY
end,
case when CPN_TYP = 'DEFAULTED' then 'D'
when RTG_SP = 'N.A.' then 'NA'
else RTG_SP
end,
null, TICKER, CPN,
case when MATURITY is null and IS_PERPETUAL = 'Y' and NEXT_PUT_DATE is not null
then NEXT_PUT_DATE
when MATURITY is null and IS_PERPETUAL = 'Y' and NEXT_PUT_DATE is null and FINAL_MATURITY is not null
then FINAL_MATURITY
when MATURITY is null and IS_PERPETUAL = 'Y' and NEXT_PUT_DATE is null and FINAL_MATURITY is null
then dateadd(yy, 50, getdate())
else MATURITY
end,
CRNCY, COUNTRY_GUARANTOR, PRICING_SOURCE, null, AMT_OUTSTANDING, AMT_ISSUED, null, COUNRY_BUSINESS_RISK, ID_BB_UNIQUE, ID_BB_COMPANY, null, null, S_SECURITY_SQ_NO, LEVEL3,
NEXT_PUT_DATE, null, CNTRY_ISSUE_ISO, TRADE_CRNCY, null, LEVEL2, LEVEL4, ISSUE_DT, CPN_FREQ, null, null, DAY_CNT, CPN_TYP, FIRST_CPN_DT, FLOATER, BASIC_SPREAD, null --Added for artf512786
from Data_ora(index id_bb_unique_idx) where status = 1 and secId is null and ID_BB_UNIQUE is not null
UNION
select
secId, ID_CUSIP, ID_SEDOL1, ID_ISIN, SECURITY_PRICE, null, BASIC_SPREAD, ISSUER, SECURITY_DES,
upper(MARKET_SECTOR_DES) + 'BOND',
case when CPN_TYP = 'DEFAULTED' then 'D'
when RTG_MOODY = 'N.A.' then 'NA'
else RTG_MOODY
end,
case when CPN_TYP = 'DEFAULTED' then 'D'
when RTG_SP = 'N.A.' then 'NA'
else RTG_SP
end,
null, TICKER, CPN,
case when MATURITY is null and IS_PERPETUAL = 'Y' and NEXT_PUT_DATE is not null
then NEXT_PUT_DATE
when MATURITY is null and IS_PERPETUAL = 'Y' and NEXT_PUT_DATE is null and FINAL_MATURITY is not null
then FINAL_MATURITY
when MATURITY is null and IS_PERPETUAL = 'Y' and NEXT_PUT_DATE is null and FINAL_MATURITY is null
then dateadd(yy, 50, getdate())
else MATURITY
end,
CRNCY, COUNTRY_GUARANTOR, PRICING_SOURCE, null, AMT_OUTSTANDING, AMT_ISSUED, null,
COUNRY_BUSINESS_RISK, ID_BB_UNIQUE, ID_BB_COMPANY, null, null, S_SECURITY_SQ_NO, LEVEL3, NEXT_PUT_DATE, null, CNTRY_ISSUE_ISO, TRADE_CRNCY, null, LEVEL2, LEVEL4,
ISSUE_DT, CPN_FREQ, null, null, DAY_CNT, CPN_TYP, FIRST_CPN_DT, FLOATER, BASIC_SPREAD, null --Added for artf512786
from Data_ora(index id_bb_unique_idx) where secId > 0 and ID_BB_UNIQUE is not null


Thank you!