peformance difference on using -r option in bonnie++

We are doing disk i/o performance using bonnie++ on remote disk by mounting it on my local system. The ram of my local system is 10gb. Because of that we have to provide file double the size of ram. It is taking a lot of time in performance test as we are also using option -b for fsync option. If we use -r option to specify the ram, will it be any difference in performance testing or is it ok to use this option.