BUG when turning portrait

Hello !
I’m doing a magazine reader app in F7, works nice, but there’s only one problem
When i turn the cellphone (this happens in android and iOS) in portrait, the app lags, a black screen appears and switches between an app screen and this black screen, and after about 2 or 3 seconds, the magazine appears normally. Does anyone know how to get this lag? Have someone ever had a similar problem?
Ignore if there’s some errors, i’m brazillian and my english isnt perfect :frowning: