Thanks Vlad,

>
> You have avg hash len = 10. Double hash slots and avg hash len will be shorter two times, i.e. you can expect 5. I'd increase hash slots by 5-6 times for the start.

I thought I read somewhere that the maximum value was 2048, but I now notice in the 2.1 release notes that the maximum value is actually 65536.
( http://www.firebirdsql.org/rlsnotesh/rlsnotes210.html )

I will start looking for a prime numbers around 6000.

>
> And no, you don't need to restart service - full disconnect is enough. First connection will re-create lock table using new parameters.

Great. Thanks.

Adam