Large nested/recursive object variables causing memory and performance issues

While developing a large drupal project I lately encountered a strange drupal problem that causes memory and performance issues.

When I var dumpped a variable in node I noticed that drupal is handling with large object variables that store 10 times, maybe 10 times duplicated data.
Sometimes, when I var_dump a variable in a view, the object is so large, php runs out of memory only by trying to output the contents of the object to buffer.
So actually I'm handling with nested/duplicated objects passed to templates that waste 20 times more resources.

Sometimes, even single cck field variable ( that should just contain the array with value), I end up with huge nested object that also contains other fields...

I tried disabling several modules but nothing seems to help...
Anyway, I think this is also the reason why php is using 60, on some pages even 120mb of memory.

Has anybody encountered problems like mine? Help would be deeply appreciated.