Source: C++ Programming for the Absolute Beginner, 2nd Edition by Mark Lee
Example:
The main operation of the computer is executing these instructions. Fetch the next instruction. Execute it. Fetch the next instruction. Execute it. Over and over again. Except this all happens very fast. A 1 GHz CPU can execute one billion instructions per second! Nothing to shake a stick at (though I’m not sure why one would want to shake a stick at things… the motivation seems to be lacking).
If you've got more of something than you can shake a stick at, then you have a lot of it. That's the original expression. Obviously, a billion instructions per second is a whooping number. You sure can try and connect the two ideas—the idiom about having a large quantity of something and the fact that most computers run billions of operations per second these days, but to be perfectly honest I'm not exactly sure where the author is going with his joke (he intentionally distorts the original expression) which is apparently a play on this idiom. Any idea?
Best Answer
The real meaning of the idiom "Nothing to shake a stick at" is that something is not very impressive. Here is a reference to its origins. Another, more understandable, version is "Nothing to write home about".
At first reading, I thought is was appropriate, after all 1GHz processor isn't much these days, but the exclamation mark indicates that he was impressed at the time of writing.
He has probably mixed up his idioms. The "not sure why" is just a remark about the absurdity of the idiom.