I'm having issues with typing on my Macbook Pro

So recently, I've been experiencing problems on my Macbook Pro.

I got it in early July 2014, and I didn't have any problems with it until not too long ago.

Sometimes, when I'm typing, it will lag, and then whatever I was typing will appear after about 3 seconds of lagging.

I ran a full scan on Avast!, and it did not detect any infections, however, it was unable to scan 157 files, but it successfully scanned nearly 650,000 files.

On Friday, I accidentally downloaded the browser hijacker "Installmac," when I thought I was downloading Skype. I then downloaded Avast!, and then I used it to delete the brower hijacker's files. There is none left.

I've tried restarting, but it has not solved the problem.

What is the problem? What should I do?

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Adding on, the screen freezes/lags as well! As stated before, it is only for 3 seconds, but I would rather have it not freeze/lag at all.

 

@Zcott

Really? Avast! could be the problem?

No offense, I kind of disagree with you. From all the reviews and recommendations it has, it seems decent, and because of that, I doubt it is the problem.

 

@yjchua95

Alright. I only downloaded it because I accidentally downloaded that browser hijacker "InstallMac" (Long story, don't ask), and I wanted to make sure all the files from it were gone.

Is there any specific way to delete it, or do I just drag the program and any related to it straight into the trash on my Mac?

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Alright, I just deleted avast!

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After deleting it, things have been running smoothly! Thanks guys!