What is important to remember is thats "Apps" and "Data" are two differnet things !!!!!!!
What i now undertand, is after the SD card is formatted and his in internal Storage.
We can put "Apps" in either Internal or on the SD Card.
"Data" can also be either on Internal or SD CARD
But "Data" is someting quite different...
So what is "Data" then.....
Well the way i see it it used by the Android file System and has dramatic impact on performance in some cases.
Well if you move the "Data" to SD card you will see your Shield be quite slower than if it uses the the Faster Internal memory. But, depending on how th App/game is coded you might not see the differences.
But for an App like KODI (which is known to be pretty I/O intensive) the differences are obvious.
OK, what can i do if you moved the "Data" to the SD Card... The fix is quite easy just go in < Settings - Storage & Reset - Internal storage > and select "Move Data Now". I would recommend a reboot of the SATV at the end just to make sure everything is fine.
So what i learned is that performances of the SATV is affected by the location of "Data"
For performances, i would recommend placing the "Data" on the internal storage and leave it there.
Hope this can help with others with performances problems on KODI and in the SATV.
So basically it's not the fault of Nvidia, the SATV or KODI, it ususally caused by the users themselves... just like i did....
In my case, there was no reason to use an external drive or USB Key to fix it up.