I actually concur on this one, funny I've never noticed it before.
Although I'm not getting anything nearly as dramatic. When you open up the options form, it's copying simopts to tmpopts. This includes total simulation time, run cycles, etc.
When you click change, tmpopts is being copied to simopts, which means all the simulation run time variables in simopts are being overwritten with the values of the sim when you opened the options form.