I am VF page which display records for a custom object. When there are a large number of custom records - I get: HEAPSIZE 6014176 error on page.
Any tips?
You're retrieving too much data and running into an Apex governor limit. You will need to reduce the amount of data you're retrieving and working with.
Update
One way to deal with this is to paginate the records returned. Salesforce provides a StandardSetController that allows you to easily work with lists and paginated results; in short you can create your own list view with it.