4 months into the job and I'm bored?

I found a new job not too long ago (4 months ago). There was a steep learning curve in the first 2 months which kept me going. I like to problem solve and it took me a while to figure things out. I enjoy learning new things. This month is the 4th month and it appears like I'm doing stuff way too fast. Maybe because I'm getting better at it or maybe I'm a quick learner. There are times when I'm done with everything and I'm in idle mode (honestly, I spend only 2 hours per day doing real work and the rest is doing nothing much). Some days are very busy which keeps me working for 4 days non-stop then sometimes sit for 2-3 days straight doing nothing again.
There is another employee who started at the same time as me. That person takes VERY long to finish his/her projects. If my manager didn't hire that person, I could have done double the amount of work. I have no idea whats taking so long for my colleague to finish. It's about the same level of difficulty. Thank god we work on individual projects rather than team-based. It appears like my colleague can NEVER meet deadlines for some reason whereas I am pretty much done everytime. It usually takes about 5 days in total to finish a medium project by myself whereas it would take my colleague about 10-15 days.
I get paid very decent. Work-life balance. Long lunch breaks. Nobody monitoring me. What do you think? Is it because i'm overqualified? I'm too good for the job? Or is it time for me to look for a new job? There are still a lot of things to learn but some days I'm just looking at my monitor doing nothing or waiting for the next project to come.
There is another employee who started at the same time as me. That person takes VERY long to finish his/her projects. If my manager didn't hire that person, I could have done double the amount of work. I have no idea whats taking so long for my colleague to finish. It's about the same level of difficulty. Thank god we work on individual projects rather than team-based. It appears like my colleague can NEVER meet deadlines for some reason whereas I am pretty much done everytime. It usually takes about 5 days in total to finish a medium project by myself whereas it would take my colleague about 10-15 days.
I get paid very decent. Work-life balance. Long lunch breaks. Nobody monitoring me. What do you think? Is it because i'm overqualified? I'm too good for the job? Or is it time for me to look for a new job? There are still a lot of things to learn but some days I'm just looking at my monitor doing nothing or waiting for the next project to come.

Comments
+1
You may be more talented than your co worker. It looks like you don't know why he is missing the delivery date, so I wouldn't make to many assumptions. I would just offer some assistance to your boss so he/she knows and he/she can make the decision.
If you are getting your work done quickly and correctly, then that's a good thing. I have a fair amount of downtime at work and I've used it to earn 9 certs, my AAS degree and close to 1/2 my B.S. in IT degree.
I'd ask for more responsibility or pick some certs to work on. Employers like to see you enhancing your education.
If you have four spare hours each day, I would allocate 2-3 to improving your team's performance and 1-2 to self-improvement. Remember that, if your goal is to improve your team's performance, you need to have a good relationship with your co-worker. Strive not to be adversarial nor arrogant.
As others have stated, work on certs or furthering your education.
If your colleague is having issues, try working with them and find out what they are struggling in. Maybe you could teach them and become a mentor. Maybe they're working on things that you have little experience in and working with them will help you gain that experience.
Is there more advanced techs/admins in your office? See if they have anything they would let you assist them with.
It's all about learning and gaining experience. Just because you have your current duties down doesn't mean you should sit idle. Find a way to grow - be it through self-studying or hands-on by helping others.
FWIW - I wouldn't look at leaving after 4 months - I would stay at least a year or two.
Task: (Time is money)
*Study/Lab
*Learn other team members duties
*Help out the other guy who is struggling if you can.
Most of you have suggested:
-Self-study and learn
-Improve team performance and help colleague
1. My colleague spends so much time talking on the personal cellphone (walking in and out of the cubicle)
2. Eating peanuts or seeds all afternoon on certain days (I hear cracking noises non-stop)
3. Chatting on MSN or some kind of chatting tool (I'm guessing because I hear a lot of keyboard typing noise all day when our job doesn't even require much typing)
Anyway, back to my situation...self-studying sounds like a good idea. But, I don't think it would be appropriate to open up a textbook at my desk in the meantime. I'm still new to the work environment. My manager comes by at random hours by surprise (maybe every 2-3 days). I could surf the internet but everything is tracked and don't want to be the first person to get fired.
These days I'm just doing things very slow...a project that would take me 3 hours to do...I would spent 5-6 hours on it...I would work on it...then get a coffee then work....seems more better than doing it quickly and sit idle at my desk.
Maybe he is doing documentation? Just as you said... you are just guessing. You have no idea. I would stop assuming.
Not to be rude, but I would stop worrying so much about him and worry about yourself.
This. I have all my ideas and long term/unannounced projects listed out. Whenever I hit a slow day/week, I open up that list and revisit them.
CCENT: 04/16/2012
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You say that now ... it get's old after a while though .. I've been there - and whilst the idea of studying sounds great - you won't do that every day especially not in an environment where people interrupt you - even if it is just nonsense and in short bursts ...
In my current job I am commuting 1hr40 each way and also thought "I have sooo much time to study" on the train - even that can get old and at some point you are so numb that you can't be ar**d to do anything, reading, listening or otherwise .. Same with boring jobs ..