OpenGLES, X11 and Qt Quick 2

[mrdebug]

My application based on Qt 5.5 (Quick) is very slow on raspberry pi. It has only a graphic timer and one cpu core is all time at 100%.
Is there a way to speed it up?
I know Qt Quick 2 can't use framebuffer but in youtube I see a lot of applications working well using OpenGLES, X11 and Qt Quick 2.

[topguy]

My application based on Qt 5.5 (Quick) is very slow on raspberry pi. It has only a graphic timer and one cpu core is all time at 100%.
Is there a way to speed it up?

Depends probably on how you have implemented it, sound like something is polling or doing display updates continually.

I know Qt Quick 2 can't use framebuffer but in youtube I see a lot of applications working well using OpenGLES, X11 and Qt Quick 2.

Not sure why you claim "Qt Quick 2 can't use framebuffer", I have used OpenGLES from QML on many Qt5.x versions. But you don't use it together with X11 its "either/or".