I have run stress tests against Firebird and a handful of other
Database Management Systems, and I have made the following
observations:

- For insert, update & delete, the performance was EXCELLENT
and no worse than for big commercial DBMS
- For simple selects, the performance was worse than for any
other DBMS tested.
(in both cases, use of primary key indexes was made, e.g.
SELECT/UPDATE ... WHERE ID = ?)

- Also, for operations that require index scans or full table scans,
the performance was 10 times as bad as for the worst competitor.

I post this because I am curious if somebody can explain results like
that: does Firebird use some kind of indexes that would explain such
a behaviour?
I used the out-of-the-box configuration of Firebird: was that a
mistake?
Any other clues?

Thank you,
Laurenz Albe