In Boot Camp the entire Mac would be a Windows PC. This would boot the entire Mac into Windows only, so that Windows and OS X are not both trying to use the Mac at the same time. In that case your other option is to put Windows on its own drive partition and run Boot Camp. Even better if the Mac has solid state storage.īut if you are for example running Parallels on an older Mac with 4GB RAM and a dual-core CPU off a hard drive, it is possible that running Windows inside OS X may be too high of a demand and it might seem slow. Something like a quad core CPU with 8GB RAM or more with few other Mac applications running should run Windows and Quicken inside it OK. If your Mac has enough CPU power and enough RAM to run the equivalent of two computers, you should not see a Parallels slowdown.
Running Parallels means you are running a complete Windows installation inside OS X. The general conclusion you should be drawing from the responses is 'Parallels will not slow you down unless your Mac is under-equipped to run two OSs at the same time.'