Maybe, displaying the bytecount of every output expression in tooltips or status area:

$Post = Tooltip[#, ByteCount[#]] &

or

$Post = StatusArea[#, ByteCount[#]] &

To delete all generated cells upon closing a notebook, you can use

SetOptions[EvaluationNotebook[], NotebookEventActions -> {"WindowClose" :>   FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]}]; 

inside the notebook.

Or, you can select Selected Notebook or Global Preferences in the Options Inspector and add

{"WindowClose" :>  FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]} 

to the NotebookEventActions line.

Maybe, displaying the bytecount of every output expression in tooltips or status area:

$Post = Tooltip[#, ByteCount[#]] &

or

$Post = StatusArea[#, ByteCount[#]] &

To delete all generated cells in the notebook, evaluate

FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]

or

FrontEndTokenExecute["DeleteGeneratedCells"]

To delete all generated cells upon closing a notebook, you can use

SetOptions[EvaluationNotebook[], NotebookEventActions -> {"WindowClose" :>   FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]}]; 

inside the notebook.

Or, you can select Selected Notebook or Global Preferences in the Options Inspector and add

{"WindowClose" :>  FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]} 

to the NotebookEventActions line.

Maybe, displaying the bytecount of every output expression in tooltips or status area:

$Post = Tooltip[#, ByteCount[#]] &

or

$Post = StatusArea[#, ByteCount[#]] &

Maybe, displaying the bytecount of every output expression in tooltips or status area:

$Post = Tooltip[#, ByteCount[#]] &

or

$Post = StatusArea[#, ByteCount[#]] &

To delete all generated cells upon closing a notebook, you can use

SetOptions[EvaluationNotebook[], NotebookEventActions -> {"WindowClose" :>   FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]}]; 

inside the notebook.

Or, you can select Selected Notebook or Global Preferences in the Options Inspector and add

{"WindowClose" :>  FrontEndExecute[FrontEndToken["DeleteGeneratedCells"]]} 

to the NotebookEventActions line.