Can I get a virus on my iPhone 5?

Lately my phone isn't leaving apps as quickly… And is lagging. Can I get a virus from websites on my iPhone? Because I go on a lot of sites on my phone. Please help because I just got the iphone 5 and if there's a problem I'm taking to the apple store

The iPhone doesn't give back resources… Double click the round button at the bottom and a list of apps will pop up, clear those out to free up your ram.

They say Apple products are impervious to viruses, however that's simply not true. Any device that is connected to the internet can get a virus, including but not limited to, psp's, ps3's, xbox, etc. There is a smaller amount of viruses specifically for Apple devices because since November of 2001 there wasn't much of a following for Apple products.
Now, onto your original question. As with any other electronic device, it'll slow down after a while. I'm guessing you got it sometime around October or November. The phone shouldn't be too slow by now, a few steps for you to try.
Try double clicking the home button and clearing all the recently used applications.
Text messages also take up a lot of RAM. Delete the ones you can to conserve space. Most phones now have an option to save a limited number of text messages.
Try resetting your phone, not just rebooting. Hold the home button and the power button for 12-15 seconds until the Apple logo appears.
As for whether or not you have a virus, it's highly unlikely. Unless you've been visiting sites known to give viruses… ;)

Very unlikely, trust me mate.