First of all, thank you very much for not including a poll in this post.

While the OS information is appreciated, additionally helpful would be your RAM and graphics card information. This is most likely the result of natural slowdown. Have you tried restarting yet after this happens? How often do these dips happen? It's oftentimes a natural thing that happens with computers, but if it is happening more than once per minute, you may have some sort of problem.

~ Traft