Can I install DDR3 1333 RAM into a notebook that is currently running DDR3 1066 and will it have any effect on performance?
If the memory is otherwise identical, it will work fine at the lower speed. The clock speed specified for a memory module is the MAXIMUM speed that it will work at. There is no harm in using in a system configured to go slower.
lookup the manual on your notebook, it should mention all the different speeds of ram the motherboard supports.
Old question, but only partially answered, as the question has two parts; the second part is “will it have any effect on performance?.
And the answer is yes. Not really noticeable under common routine tasks; but on heavy tasks, the faster speed will be noticed up to a 15% increase from 1066 to 1333 in the different stream memory tasks, as shown in the following test.