Oracle 11.2.0.4 RDMBS spatial performance

Hi,

We have a spatial application on a 11gR2 db (version 11.2.0.4 64 bit) and
we experience performance issues. We I look a the db I see two queries which  take care for > 90% of the db activity:

1) SELECT rid , start_1, end_1 , start_2, end_2
FROM MDSYS.SDO_TXN_IDX_INSERTS
where sdo_txn_idx_id = '21F88$' and :bnd_1 <= end_1 and start_1 <= :bnd_2 and :bnd_3 <= end_2 and start_2 <= :bnd_4

and

2) SELECT PRECX, PRECY, PRECZ, DIEPTE, PARA, GEOMETRIE, ID, LOKAAL_ID, INWIN_INSTANTIE_ID, INWIN INTO :PrecX, :PrecY, :PrecZ, :Diepte, :Para, :Geometrie, :ID, :LokaalID, :InwinInstantieID, :Inwin
FROM DGDTW_TOPOPOINTS
WHERE ID =
(SELECT MAX(ID