You've kinda/sorta jumped into the deep end of the pool, what with digging into this level of optimizer details so soon as a ASE 'newbie'. It'll just take some time to absorb all the details and figure out how to connect all those darn dots. :-)
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NOTE: While I work with the SAP/Sybase ASE product, I do not work with SAP applications; with that in mind and fwiw ...
On the other hand, since this is a SAP application and ... ideally ... the DBA shouldn't have to worry about these kinds of details (ie, SAP's tried to remove the need for the DBA to know a lot of details about the underlying RDBMS), I'm wondering if there could be an issue with the steps taken to copy the EP1/300 database to the EQ1/210 database?
I mean, surely more companies would be having this kind of performance issue after copying databases between SAP systems (eg, PRD to QAS), so I'm wondering if there could be an issue with how your (system) copy was performed? Perhaps a missed step? Perhaps some ASE-specific steps you may not be aware of?
A quick SCN search shows another recent post of yours regarding a ABAP query performance issue - ABAP Query index failure - after a system copy; and there was a mention of looking at table stats.
Just curious ... could these performance issues be indicative of a misstep during a system copy?
It might be of interest to review whatever KBA/notes are related to a ASE-specific system copy ... see if something was missed? If these kinds of issues persist it may be of interest to start a discussion re: a ASE-specific system copy to see if others are having any issues, or if there are some additional KBA/notes to consider ... ?