I need to render an object with a lot of vertex and I only know one method to render:
In function paintGL clear the buffers and call the render. The problem I found is at each “updateGL”, I remade the render of the object and the app (with Qt) goes more and more slow.

Someone tell me that there’s a way to make a render more eficient, can someone send me a “guide” or a link to learn how to do it? Thanks

Google for VBO (vertex buffer objects).
related functions: glVertexPointer, glBindBuffer, glBufferData, glDrawElements

I remade the render of the object

Do you mean you are compiling the display list each time ? If so, simply compile it the first time, then call the list the other times.