variable screen performance in report

In my project we are having somany master data objects,

we have to find the performance of selection screen ,earlier we have only display as selection screen as key now according to our client requirment we are providing both key and text in sleection screen with long text , how can i find these master data objects performance in variable screen.

The SAP std out of the box setting for an Infoobject is usually the key.( Sometimes text )

We are now making changes to almost all info objects to display as key and text, and depending on what business is asking we are changing to Long text, medium or short.

Investigation required

1) how does it affect the performance when we do F4 help

2) how does it help in search by text

3) what difference does it make when searching by key vs text.

My feel is if we show the key and text , definitely the key comes from Dimension table and the text will be fetched from the text table of the master data attribute

And hence for business partner etc it might really affect the time taken to fetch the variable values.

please help how to find the performance of variables.