>SELECT r.LINENR, r.COMPONENTNR, MAX(r.SUMWEIGHT)-MIN(r.SUMWEIGHT) as sumweightdiff
>FROM GRAVCOMPDATA_LONG r
>where r.GRAVTIMESTAMP Between CAST('NOW' AS TIMESTAMP) - 60/1440e0 AND CAST('NOW' AS TIMESTAMP)
>group by r.LINENR, r.COMPONENTNR

You forgot to mention the main part of any optimization task, the chosen PLAN. This answer is therefore based on expecting indexes not to be optimized for this query yet.

Is there any GRAVTIMESTAMP > 'NOW'? If not, then add a DESCENDING INDEX for GRAVTIMESTAMP and change your query to:

SELECT r.LINENR, r.COMPONENTNR, MAX(r.SUMWEIGHT)-MIN(r.SUMWEIGHT) as sumweightdiff
FROM GRAVCOMPDATA_LONG r
where r.GRAVTIMESTAMP >= CAST('NOW' AS TIMESTAMP) - 60/1440e0
group by r.LINENR, r.COMPONENTNR

Hopefully, this will change the PLAN and the execution time improve.

HTH,
Set