ANSWER: The answer to your question really depends on how safe you are when you use your Nexus 7. And how closely you pay attention to requested permissions when installing a new app.
Start by being smart
First things first. If you download and install all of your apps from Google Play, you should have nothing to worry about as Google scans all of the apps it puts in its app store before releasing them to the public. But, as you may already know, you can install apps from just about any website using your Nexus 7. This is where you can get yourself into trouble and is a practice I would definitely avoid.
Another way to get in trouble is to ignore the permissions an app is requesting when you install it. I tend to look for things that don’t make sense to the app I am installing. For instance, if I am installing a game, I wouldn’t expect to see a permission requesting that the app can send SMS text messages on my behalf.
Personally, I have been using Android devices for nearly two years now and have yet to get a single virus or malware instance on any of my devices. But like I mentioned above, I only install apps from Google Play and I always review all of the requested permissions when installing a new app. And if I don’t like what I see, I don’t install the app.
Anti-virus apps do more than just scan for viruses
Now, this isn’t to say that anti-virus apps for your Android devices are a waste of time. Many of them will protect you against apps installed outside of Google Play and will warn you when apps are doing something they shouldn’t. Better yet, they often come with additional features like find my device, remote lock or data backup that you might like regardless of whether or not they protect you against viruses and malware.
As to your question of whether or not they will slow down your device, I would say yes they will. This is just the nature of any background scanning application. It’s going to take up memory and processing time to do its job. But it probably won’t be as bad as you think unless you tend to run a lot of apps at the same time.
Which one is the best?
So which anti-virus app should you install? I’m not sure there is a clear-cut winner but a year-old study done by AV-Test inspecting 41 Android virus scanners listed the top 7 as Avast, Dr. Web, F-Secure, Ikarus, Kaspersky, Zoner and Lookout.
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