The below Query runs very slow

Question

SELECT
ACT1.PROJ,
ACT1.ACT,
ACT1.VER,
ACT1.DS,
ACT1.UC,
ACT1.ACT_RN,
PRED1.PRED,
PRED_DS.DS,
PRED_DS.UC01 ACT_TYPE ,
PRED1.RN,
SUCC.SUC
,SUCC.SUC_NAME
,SUCC.SUC_TYPE
,SUCC.SUCC_RN
FROM
(SELECT A.PROJ , A.VER , A.ACT , A.DS , A.UC01 UC , B.RN ACT_RN
FROM PM_PORTAL.AV_ACTIVITY A , PM_PORTAL.AV_RESREQ B
WHERE A.PROJ = B.PROJ(+)
AND A.ACT = B.ACT(+)
AND A.VER = B.VER(+)
AND A.VER = 50
AND A.PROJ LIKE 'BOM_%'
AND A.UC01 = '560'
) ACT1 ,
( SELECT A.PROJ , A.ACT , A.VER , A.PRED , B.RN
FROM PM_PORTAL.AV_RELN A , PM_PORTAL.AV_RESREQ B
WHERE A.PROJ LIKE 'BOM_%'
AND A.VER = 50
AND A.PROJ = B.PROJ(+)
AND A.PRED = B.ACT(+)
AND A.VER = B.VER(+)
) PRED1,
( SELECT DS , UC01 ,ACT ,VER , PROJ
FROM PM_PORTAL.AV_ACTIVITY
WHERE PROJ LIKE 'BOM_%'
AND VER = 50
) PRED_DS ,
(SELECT A.PROJ , A.VER , A.ACT SUC , A.PRED , B.DS SUC_NAME ,B.UC01 SUC_TYPE , C.RN SUCC_RN
FROM PM_PORTAL.AV_RELN A , PM_PORTAL.AV_ACTIVITY B , PM_PORTAL.AV_RESREQ C
WHERE A.PROJ = B.PROJ
AND A.ACT = B.ACT
AND A.VER = B.VER
AND B.PROJ = C.PROJ
AND B.ACT = C.ACT
AND B.VER = C.VER
) SUCC
WHERE ACT1.PROJ=PRED1.PROJ(+)
AND ACT1.ACT=PRED1.ACT(+)
AND ACT1.VER=PRED1.VER(+)
AND PRED1.PRED = PRED_DS.ACT
AND PRED1.PROJ = PRED_DS.PROJ
AND PRED1.VER = PRED_DS.VER
AND SUCC.PROJ = PRED1.PROJ
AND SUCC.VER = PRED1.VER
AND SUCC.PRED = PRED1.PRED
--Execution Plan
SELECT STATEMENT, GOAL = CHOOSE               293     1     337
NESTED LOOPS               293     1     337
NESTED LOOPS               290     1     305
NESTED LOOPS               287     1     242
NESTED LOOPS               282     1     206
FILTER                         
HASH JOIN OUTER                         
VIEW     PM_PORTAL_READ          65     2     194
NESTED LOOPS OUTER               65     2     190
TABLE ACCESS BY INDEX ROWID     TRN_ARTE     AV_ACTIVITY_NPART     59     2     126
INDEX RANGE SCAN     TRN_ARTE     AV_ACTIVITY_1_NPART     55     2     
INDEX RANGE SCAN     TRN_ARTE     AV_RESREQ_1_NPART     3     35     1120
VIEW     PM_PORTAL_READ          210     101     4646
HASH JOIN OUTER               210     101     6868
INDEX RANGE SCAN     TRN_ARTE     AV_RELN_1_NPART     161     101     3636
INDEX RANGE SCAN     TRN_ARTE     AV_RESREQ_1_NPART     48     35     1120
TABLE ACCESS BY INDEX ROWID     TRN_ARTE     AV_ACTIVITY_NPART     3     56     3528
INDEX UNIQUE SCAN     TRN_ARTE     AV_ACTIVITY_1_NPART     2     56     
INDEX RANGE SCAN     TRN_ARTE     AV_RELN_1_NPART     5     101     3636
TABLE ACCESS BY INDEX ROWID     TRN_ARTE     AV_ACTIVITY_NPART     3     56     3528
INDEX UNIQUE SCAN     TRN_ARTE     AV_ACTIVITY_1_NPART     2     56     
INDEX RANGE SCAN     TRN_ARTE     AV_RESREQ_1_NPART     3     35     1120

Answer 1

Here's the verbatim response I gave yesterday to another user also posting his SQL and asking the same question.. why is it slow?
Who says it is not already running as fast as possible?
In order to solve a problem, you need to know the problem. Stating something like 'a query is slow and should be faster' is stating an opinion - it is not describing a problem that can be resolved.
My suggestion is to turn a complex problem, into a bunch of smaller and simpler problems. If you suspect that the query could be faster, pull it apart. Test each step/component of the query in isolation. E.g. start with a single table and progressively add joins to determine what the CBO does with each additional join, what you're asking Oracle to do ito processing, and not only checking that the CBO does not make obvious errors, but that what you're asking via SQL is the best approach to get to the answer.