Change structure of thumbnail folder

[saosangmo]

hello,
Because I want to improve I/O speed, so want to change the default thumnbail folders like the below tree:

Root
-Folder 1
-.tmb (of Folder 1)
---Folder 1.1
---.tmb (of Folder 1.1)
---Folder 1.2
---.tmb (of Folder 1.2)
-Folder 2
-.tmb (of Folder 2)
....

How I can do this?
thank you so much!

[nao-pon]

@saosangmo #1795 will be helpful.