Acronis True Image Home 11 - V. Build 8.064 - Backup ist very slow

I testet the image of the system-HD on an separate harddisk (SATA (source) -> IDE (target)):

- without anti-virus (Panda AV 2010 pro - antivirus + firewall) - 12 minutes
- with activated Anti-Virus - over 50 minutes - it can be that the the system hangs bevor the
image beginns

Is it possible ? Any experience with anti-virus-programs ?

greats,
JoMo