In case anyone's wondering, unlike setting priority or limiting the number of threads, BES will actually limit the process CPU usage, so if I have 4 threads running on my 4-core i5, setting BES to limit 50% will cause the miner to consume 50% total CPU with all 4 threads, which will typically be 50% usage on each core.

Something I noticed with the way I set my miners' process priorities (I'm using TaskInfo persistent priority) is that the miners' threads still run at priorities higher than 1 (like 3 or 4,) which causes a problem with certain software I'm running that have threads at priority 1 for some reason.  Instead of dedicating an entire core to this stupid software, I can just limit my miner by 2-5%, leaving enough for those priority 1 threads to fit in, while still giving most of the CPU cycles to the miner.