When typing a formula in to the FormulaBuilderDialog it is painstakingly slow. For each character typed it will freeze for several seconds making it a not so fun experience. Anyone seen this before or know of any causes?
No, that's never happened to me before and I've never heard of it happening. The FormulaBuilder actually uses a timer to allow the UI to remain active while you type and only compile the formula when there is a pause, so what you are describing doesn't seem possible.
What version of the controls are you using?
What operating system are you running?
Windows XP SP2 and Version 8.1.20081.100.
I just went and double checked it seemed more responsive than last week but if I typed a formula at normal pace there was some serious lag and the formula wouldn't appear on screen until much more than several seconds after I finished typing.
I'm afraid I have no explaination for that. It works fine on mymachine with the same version. Perhaps you need to get the latest Hot Fix:
My Infragistics Keys and Downloads - Download Anything and Everything You Own
If that doesn't help, you should Submit an incident to Infragistics Developer Support. Maybe they know of an issue that I am not aware of.