Serial Monitor laggy if not scrolling

I use debug prints in my code. And I noticed once the scroll wheel is not exceeded, the serial monitor printing lags. Once the bottom is reached and the monitor has to scroll upwards for new text it is very fluent again.

This is very annoying as I am trying to debug time critical code. I have to first fill the whole screen to debug my code.

Using IDE 1.6.9 from git, linux x64, Arduino Leonardo.

Reproduce this in Arduino IDE 1.6.9 on Linux x64 with an Arduino Leonardo, comparing serial output while the view is away from and at the bottom. The issue is done when continuous serial printing remains responsive without first filling the monitor.

Written by the indexing model from the issue text.