views with outer joins used in select with union

Hello,

Using IQ 15.4 ESD#6 .

I'm looking for any tips or recommendations regarding the use of views that include  select  left/right outer joins, which afterwards they are referenced by a select statement that uses select union, i.e:

create or replace view1..

select left outer join... from <tables>

..

go

create or replace view2..

select left outer join..from <tables>

..

go

select <cols>

from view1 union select <cols>  from view2...

go

We can have <N> views with <N> UNION statements which could be  used in the SELECT that references them.

So the question is  if this is a good way or is it preferable to replace the views with  Temporary tables..?

Basically these queries are performing slowly and spending a lot o time in the "fetch process". I'm attaching just a sample query plan as HTML.

Also we  activated sp_indexadvisor and some HG recommendations appeared

Thank you

Regards

Jose Miguel