Dear Experts,
I have selected Bitdefender for my new PC security product. After installing it I started to run a System Scan, scanning "everything".
The scan started but my PC dramatically slowed down, I can't even open a website, however, no significant CPU load (below 10-15%).
I tried to stop scanning but I required 2-3 minutes(!)
to stop. In the meanwhile I recognised that I have 0 (zero) free space on my system SSD, however I had 10GB before. 
Fortunately, it "restored" after some 5 minutes after stopping the scan. 
I also recognised that it created a folder c:\Program Files\Common Files\Bitdefender. Its size also varies by a huge extent.
Why it is that? Is it a normal phenomenon to eat up disk space by that much? What shall I do? Is it better to reinstall it onto my HDD instead of my SSD, where there is much more free disk space?
SSD is much quiker, therefore I put Bitdefender there for the faster startup.
Thank you for your help indeed! 
I have Win7 64bit, 64GB SSD (10GB free), Core i5, 8GB RAM, 2TB HDD.