Hi András, if your file system has barrier enabled ( ext4 by default has it ), ant you set forced writes ON, then massive updates will be very slow. You should decide between setting FW On or using a file system with barrier activated.
There has been a thread in this forum about this point some time ago. [1] Aldo [1] https://groups.yahoo.com/neo/groups/firebird-support/conversations/topics/125057
