SAP transaction performance issue

One of SAP standard Transaction gets hanged while saving .

I would like to know what is the use of VBDATA table .

when i Put SQL trace, the VBDATA table does not contain vbkey field value specified in below statement .Can this be the reason ....

SELECT * FROM "VBDATA" WHERE "VBKEY" =

54583AEF7DE95011E10000000A7B1111" = 6 AND "VBBLKNO" >= 0 ORDER BY "VBKEY", "VBMODCNT", "VBBLKNO" WITH RS -- OPTLEVEL( 5 ) -- QUERY_DEGREE( 1 )