대강 물으셔서 정확한 답변이 어렵군요...저도 개념들만 대강 쫙~ 쓰겠습니다...;
REGEXP이나 INSTR과 SUBSTR의 조합으로 one-SQL로 처리하신 거라면 그 외엔 성능개선방법은 크게는 없을 듯 합니다만...;

작게는 수행세션의 db_file_multiblock_read_count 파라미터의 조정이나 parallel 처리 등이 있을 수는 있겠죠...;

WITH t AS
(
SELECT '222.231.42.50' a FROM dual
UNION ALL SELECT '113.30.100.58' FROM dual
UNION ALL SELECT '4.68.110.26' FROM dual
UNION ALL SELECT '113.30.100.34' FROM dual
)
SELECT a
, LPAD(REGEXP_SUBSTR(a,'([^.]+)',1,1),3,'0') || '.'
|| LPAD(REGEXP_SUBSTR(a,'([^.]+)',1,2),3,'0') || '.'
|| LPAD(REGEXP_SUBSTR(a,'([^.]+)',1,3),3,'0') || '.'
|| LPAD(REGEXP_SUBSTR(a,'([^.]+)',1,4),3,'0') b
FROM t
;

WITH t AS
(
SELECT '222.231.42.50' a FROM dual
UNION ALL SELECT '113.30.100.58' FROM dual
UNION ALL SELECT '4.68.110.26' FROM dual
UNION ALL SELECT '113.30.100.34' FROM dual
)
SELECT a
, RTRIM(REGEXP_REPLACE(REPLACE('00'||a,'.','.00')||'.','([^.]{3}\.)|.','\1'),'.') b
FROM t
;

WITH T AS (
SELECT '222.231.42.50' AS A FROM DUAL
UNION ALL SELECT '113.30.100.58' AS A FROM DUAL
UNION ALL SELECT '4.68.110.26' AS A FROM DUAL
UNION ALL SELECT '113.30.100.34' AS A FROM DUAL
)

SELECT replace(A, '.', '') FROM T