Hi,

1. Show us stats from gstat -h from working system i do not belrve that you have 3 transactions working whole the time. I suppose here that you have transaction management problem - i guess

2. Consider bigger page size but i do not know how your insert/update scenario looks like and if this not decrease perf instead increase

3. Consider change to superserver and the best migration to FB3 superserver with bigger page cache

Regards,