What exact version of avast ?
Any other security (related) software installed ? (or did you have)
What process is using a lot of cpu time ? (and what is using the process if it is svchost)
Sorry for not including all that earlier.
The version is 2015.10.2.2218
I have Malwarebytes Anti-malware installed. But it is always disabled unless i manually open it.
The "Avast! Service" is what takes up the highest disk usage. (see attachment)
If its not Avast thats taking up the disk usage, then it'll be netsvcs svchost. Its mostly avast though.