Two years ago is a lifetime ago in terms of AV products, that could either have been avast 4.8 or avast 5, additional features have been added in avast 6 & 7 and things are done differently to try to speed things up.
Two years ago I had avast version 5, I know that things are changed with new versions, but this problem linked to the repair of avast exists since that date. Each time I done a repair I saw this increase in growth, but I thought it was a temporary problem and I deceided to ignore it. Now I have finally deceided to explain my problem here on this forum, just because it persists and also to see if other avast users have a similar issue.
Sorry I honestly can see this at all, ignore what has gone before, avast 5&6. Avast 7 when installed is about 250MB on your hard drive, if you were seeing a permanent increase every time you used Repair then it would now be consuming much more.
A Repair shouldn't increase the size (other than I have mentioned if it also does a virus definitions update), but check the integrity of the installation, that may or may not mean 'replacing' a file/s that are damaged, etc. This would generally be replacing a file with one of the same size.
So I can't get a handle on this, a repair increasing the size by over 60mb and it never coming back down.
Since my last post with an image of my avast size Reply #4, I have had another avast update, now look at the size 315mb, wow what a massive jump. This is exactly as described the creation of the new defs sub-folder for the latest definitions. When the avast housekeeping does it job and removes old defs sub-folders it will drop again or there would be no way my other image would have been showing 235mb.