Thank you for writing.
You should manipulate KeyboardSearchResetInterval property in order to increase the time between key presses, for example:
.radListControl1.KeyboardSearchResetInterval = 1000;
I hope this helps.
the Telerik team
Q2’11 SP1 of RadControls for WinForms is available for download (see what's new); also available is the Q3'11 Roadmap for Telerik Windows Forms controls.