PostgreSQL 9.2.4 using large amount of memory

Hello,

We have recently shifted to postgresql version 9.2.4 from 9.1.3. After the
migration, we observed that some of our delete queries on single table
[which have triggers, which in turn call other functions] have started
consuming large amounts of memory.

In 9.1.3, this usage was upto 25MB with the same load on the same server.
With 9.2.4 it has jumped upto ~580 MB. We are monitoring the RES column
from top output to get the memory usage.

Our migration method from 9.1.3 to 9.2.4 was take a dump, un-install 9.1.3,
install 9.2.4 & restore the dump.

I also went through the thread -
http://postgresql.1045698.n5.nabble.com/Memory-usage-after-upgrade-to-9-2-4-td5752733.html

In the thread in the end it is mentioned that there was some data
corruption & points to 9.1.6 release notes. I went through the release
notes & only thing of note that I found was the re-indexing or performing
vacuum operation in case of in-place upgrade, which is not the case for me.

Any help/pointers in debugging would be helpful.

Thanks
Bhushan