Perhaps a different work flow might be your answer.... sounds like you are erasing your last take and then re recording the take until you like what you have done?
Perhaps COMPING is a better solution... you can keep performing the part until you NAIL IT, then delete all the previous takes and keep the one you like best.
Not sure if your reason for space bar, CNTL Z, record key stroke sequence is for your manual comping process but if it is, check this out, you may like this more.
Jim
PS - after you do get a good take remember to hit CNTL S before SONAR crashes and you lose your good take. :-)