pipelining

While one instruction being fetched another can be decoded and another executed.

Much more efficient then doing one a time

w/o pipelining, FDE cycles have to go one after another. So when instruction being fetched ALU is idle (not efficient).

flushing the pipe, if you see an if statement then two possible outcomes, if you follow the wrong one then lines of code in the pipeline cycle have to be flushed out.

Programs with a lot of branching may not benefit much