My computer is pretty sluggish at the moment, and while playing games I get random lag spikes. I'm not sure if its due to my specs or the actual hard drive itself. The game in question is Civilization V but these random lag spikes happen even in games such as team fortress 2.
Not your hard drive. Your hard drive has nothing to do with the gameplay. The only thing its affects is the load time. I think your processor is your culprit or maybe bad internet connection? Because Team fortress 2 is not heavy on requirements.
Edit: i just looked at the requirements for civ 5 and it recommends 4gb of ram as well. If you don't have enough ram then the game has to wait for data from the hard drive, which is much slower than accessing it from the ram.