This is rather small value for superserver with big db
with this setting, Firebird cache is only 16MB of data ;)

Increase this settings. Calc it like buffers*page size
In your settings this is 2048*8192=16MB

But if to this db there is only one connection and it is closed and reopened you loose your cached data and speed up nothing

Regards,
Karol Bieniaszewski