Have you tried setting Ryzom to a below normal or low priority? This will improve the behaviour of background applications such as your AV, especially on single core PCs. Ryzom might be running faster on lower priority since it does not need to wait (on full CPU) for the AV to finish scanning data files that long. The taskmanager itself may be running on high priority but the shell launching it doesn't.
You can also check if your AV offers options to exclude all ryzom files from background scanning. Ryzom is not a common application and thus not likely to be subject to virus or trojan attacks.
You can also check if your AV offers options to exclude all ryzom files from background scanning. Ryzom is not a common application and thus not likely to be subject to virus or trojan attacks.