Created Unassigned: Out of memory exception [9150]

Hello guys,

I´m working with large amount of data in Excel.
What I need to do is read the data, and put it into a generic list, with some business rules.
In this process, I have the total count of 1 200 000 objects inside the list.
Often it causes an memory exception due the large amount of data, rarely the process doesn´t throw an exception.
I´ve already read the support documentation and have already used the tips for better performance, but it doesn´t works to me.
Could someone help me in this case, please?

Thanks in advance,

Thiago