Hi Mike,
I've been disturbed with the font renderig in ultratexteditor and ultraLabels. But on the forum i've seen a solution i.e. changing the textrendering mode of all the controls by using Infragistics.Win.DrawUtility.UseGDIPlusTextRendering = false, it worked fine for most of the controls. But there is a problem that header text of all the tooltips is giving a bloated effect. Check the attached picture, i've circled the header text.
Do you happen to know what font you are using for the tooltip header? My guess is that it's Segoe UI or some other anti-aliased font. If that's the case, then this is a known issue and will be fixed in the next v8.2 hot fix.