Thanks for the responses. I wasn't looking for huge gains and couldn't accept that I was stuck with 1/80 for the camera I'm currently working on (the Vivitar Ultra Wide & Slim) -- especially when the specs claim a 1/125 shutter speed. Also, I have a reclaimed disposable camera, same shutter design, that clocks between 1/125 and 1/160. So I'm sure that some modest gains are possible.
I did more exploratory surgery this weekend. Unlike the diagram, this camera uses a regular coil spring to return the shutter blade. I doubled it up around the lug and attached both ends to the shutter blade. Also, I added a tiny piece of balsa to shorten the path that the blade travels. I tested extensively. The bad news is I now have a variable speed shutter. The good news is it varies between about 1/100 and 1/125 -- up from a constant 1/80. I only see this as a short term fix however.