explain and view

Hello!

If we create view1 as select from view2
explain doesn't show execution plan  for view2.

Does it mean that optimizer will use plan, which it shows in
explain select from view2?

btw, I ask this question just beacause we need to do some optimization-
the same data and queries on Oracle works  100 and more times faster 
than in SAP DB
(4 minitues compared with 3 seconds)