Sequence of figures: gap and positional adjustment

Dear all, I am making a task in which I want to present to consecutive figures, I noticed that there is temporal gap between the two figures' presentation (fullscreen) which shows the matlab page in the background. Also, there is a positional adjustment of the elements within the figure (the elements of the figure go up a little bit and they reach their final and corrected position after about 300 ms), which I would like to eliminate.

Any suggestion?

I am using the figure and imread to upload the pictures within the figure. Thanks!