Building Development Console

I want to have a nice development console in my project. Ideally I could also use it in my chat system. I implemented something which gives good results visually but I encountered some performance problems. Profiling shows that during scrolling Graphics.Rebuild takes a lot of time. That's because during scrolling I rebuild whole screen of text lines. I'm unsure how to optimize this.

In general how should I approach rendering console? I want to have full screen of text and icons which can be be changed fast through scrolling.