Freeze when Ads exit

I've learned that custom components can take a long time to create if not handled carefully.  I'd recommend looking at what you are doing in the init() method of the custom component, and also the dependency tree of that custom component since it has to recursively create all its child components as well.

That's the thing, normally rendering a cell, including init, layout, oncontentChange... takes roughly 50ms. 
But it takes 1.6 seconds when exiting an ad. I m not even  sure why it's recreating the cell after exiting the ad player?

As a note, I have commented out everything in my custom component. It now  has no children, the init does nothing, the updateLayout() does nothing

MyComponent.brs is this : 

function itemContentChanged()
    print "Cell content changed " +m.top.itemContent.title
end function

function init()
    print "Init rowlist Cell"
end function

and the xml is this

<?xml version="1.0" encoding="utf-8" ?> 
<component name="RowListTitleAndSubtitle" extends="Group">
<interface>
  <field id="width" type="float" /> 
  <field id="height" type="float" /> 
  <field id="index" type="int" />
  <field id="rowIndex" type="int" />
  <field id="itemContent" type="node" onChange="itemContentChanged"/> 
  <field id="focusPercent" type="float" onChange="focusPercentChanged"/> 
  <field id="rowFocusPercent" type="float" />
  <field id="rowHasFocus" type="bool" />
  <field id="rowListHasFocus" type="bool" onChange="focusPercentChanged" />
</interface>

<script type="text/brightscript" uri="pkg:/components/RowListTitleAndSubtitle.brs"/>
<children>
</children>
</component>

and still, when recreating those empty cells, it takes 1.6, 2 seconds for each of them When the RAF Player is exiting. Any idea what might cause this?

I can only speculate and give you things to try out.  

1) Be sure that you are differentiating between time executing brightscript and time waiting for images to download.  It looks like you have already done this by making your custom component and empty group.
2) remove the onChange from the fields.  The number of observer callbacks invoked can cause overhead, and especially so if you have a particularly large number of BRS objects or SG components in memory.
3) RAF needs memory for video cache and will probably affect downloaded images which may be purged during ad playback.  
4) You should put a print statement in all of your functions so that you can see in real time what is happening.  a timestamp in these print statements would be helpful too.
5) Be aware of the total system resource and what other threads may be doing.  After RAF ad break ends, if you have a Task thread running or main brightscript thread doing work then it will take away from SG UI thread CPU resources.