For the lagging, that's not normal. Does your system meet the requirements? Do you have a lot of other stuff running at once?
As for the megaman style scrolling, you don't need to have separate layouts at all. You can build a scrolling system that does all the scrolling in one layout.
Make a separate object called "camera" or something like that. When your player is moving normally, have the system center to the player's x,y position, and have the camera set itself to the center of the screen. When they're in certain areas (at the edge of the place where you want to scroll) then stop the system from centering on the player. Then when they leave the screen, freeze the movement and have the camera move one screen forward (or down, whatever) and have the system center on the camera instead. When the camera stops, resume the player's movement.