The gif pictures with a WHITE-COLOR background work good in ImageViews.
But a gif picture with a TRANSPARENT background will dramaticly perform badly.

The latest-painted picture of the gif appeared while the prior-painted pictures were not being flushed.
As a result, residual images remained on the ImageView redundantly.
And the residual images won't be flushed until the the whole loop play ended.

Besides, the problem gif images performed well in Windows XP default picture and fax viewer.