Perfomance of views

Hi there.

I am currently building a system, where it would be nice to use multiple
levels of views upon each other (it is a staticstics system, where
traceability is important).

Is there any significant performance reduction in say 10 levels of views
instead of one giant, nested sql-statement ? I especially think exection
planner-wise.

The data mainly comes from one small to medium sized tabel (< 5 million
rows) and a handfull small (< 5000 rows) support tables.
The hardware will be okay for the job, but nothing really fancy (specs
are Xeon, 2G of memory, 6 SCSI-disks in a RAID1+0) . The base will be
version 8.1 provided that it gets out of beta around end-of-year.

Svenne