Why Selective Editing is running SLOW???!!!

Literally my first time using the Lightroom app in the Ipad Pro 2020(brand new) and i already encountered myself with the Selective Editing tool to be running really slow. The brush edit reflects on the photo like 10 seconds later, same with the eraser(even for a light edit like only exposure).

Few extra dets:

• Ipad Pro 2020

• 256Gb

• The photo is stored locally in my Ipad as raw Photo.

• Editing using an Apple Pencil2

• Did a total of 3 Selective Editing, and every time I do an extra one the lagging gets worst.

Also it took me about 1(min):28.99sec to see the Before-After, and 5(min):23.89sec to export THAT ONE PHOTO to the Ipad Camera Roll.

Is anyone else experiencing the same issue or did experience it and resolve it? Please help!