Pabot and Data Driver optimization

Robot Framework
1

I have 10k test cases in excel and used Data driver test template with optimize_pabot=Binary. Am using pabot for parallel execution with 10 processes but in the result I see pabot form 59 executions. Could u pls help me understand how the optimize_pabot options are working?? Though I initiated 10 processes i see 59 executions and how is that possible?? Also in a machine with 4vCPU and 16GB memory how many processes can be launched to run in parallel?? If the number of processes are more i see it is taking more time for execution what could be the reason behind it. Thank in Advance