Glossary:Bottleneck
Description
A bottleneck is a situation that arises when an underpowered component limits the performance of another component. For example, running Battlefield 3 on a single core CPU will severely impact the frame rate. Another example is not having enough RAM to run a game and the operating system, resulting in slowdowns.
Common solutions
Unfortunately, there is no surefire way to gauge if you have a bottleneck, nor what is potentially causing it. Your best bet is to find a pc gaming forum and ask around if you think you may be experiencing a bottleneck. A good rule of thumb is that if your CPU/RAM/GPU is 2 years or more older than the other components in your computer, then it may be causing a bottleneck. Use common sense though, if you put a new $400 graphics card in a 5 year old computer, chances are you will experience one or more bottlenecks.
Another way to ensure little to no bottlenecks is to research the hardware. Which combination works better: A GTX 760 with an i3, or the same GPU but with an i7? While PCs can come in millions of combinations, they're some well-established notions of coupling one common thing to another. Addressing the previous example, it is more beneficial to do the latter because the i7 is known to be one of the top CPUs out there, and that it can even handle a GTX Titan.
A common bottleneck is the hard drive, fragmentation and an overabundance of small files (which slow down disk transfers) can cause 'hard stutters' (different from microstutter). Basic maintenance of a hard drive by defragmenting (SSD's needn't be defragged, an inherent attribute) can eliminate this almost completely. If you still experience hard stutters even with no fragmentation, check to make sure your hard drive definitely is fast enough, 7200RPM is recommended, 5400RPM is acceptable.