Operation System: Windows 7 SP1, with latest KB updates.
Immunet version: 126.96.36.19988
No. I'm not using scheduled or manual scan at the time of high memory usage.
These are my programs that may have high file/disk io, but I'm not using any of them at the time of high memory usage: firefox, virtualbox, qbittorrent, mipony.
Today I noticed memory usage with clamAV enabled has dropped to ~183MB (when only using firefox typing this post). But I think it's still too high compared with other antivirus products.
[EDIT] After using PC for some time and closing all programs, Immunet still uses ~442MB.