Remove text artefacts

I had problems with the text edges showing up in the performance bar regardless of the transparent font color.

![Screenshot from 2013-03-16 23:17:01](https://f.cloud.github.com/assets/1098408/267444/4b47ccb0-8e87-11e2-8c84-8693df51af0d.png)
![Screenshot from 2013-03-16 23:16:27](https://f.cloud.github.com/assets/1098408/267445/50f76288-8e87-11e2-9337-cdc5a4ab8c26.png)

This hides the bar segment text completely with font-size, in addition to the color.