I just wanted to update everyone on the results of my recent request for help... With the kind help of both Perry Greenfield and especially Greg Couch, I have been able to resolve all of the major performance bottlenecks in the Tkinter/OpenGL Chaco/Kiva code. Yeah! The net result is that the OpenGL version now performs comparably to the wxPython version. While neither version is as fast as we (and users) would like, we think we know how to go after the remaining performance issues. However, we will probably wait until the code has matured a little more before doing any further optimization work. I just wanted to thank Perry and Greg for helping me with some nuances of OpenGL that had eluded and baffled me previously. Thanks a lot guys!!! Dave Morrill