Firebird allows remote connections to the administrative account without verifying credentials.
The default configuration of Firebird before 2.0.3.12981.0-r6 on Gentoo Linux sets the ISC_PASSWORD environment variable before starting Firebird, which allows remote attackers to bypass SYSDBA authentication and obtain sensitive database information via an empty password.
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1880
He doubled his performance by just switching the firebird client :
We’ve just built and tested ‘libfbclient.so’ from the head branch and tested
it against the release version 2.0.3. In other words, we only switched out
the client library, and left the database server itself intact at version
2.0.3.
The performance improvement is huge:
fbclient-head: 6% processing time spent in ‘futex’
fbclient-2.0.3: [...]