When the virtual machine requires a high-speed timer, the requirement is usually met by /dev/rtc on the host. In some circumstances, /dev/rtc is unavailable, leading to slowness in the guest. The main symptom is that the virtual machine's clock fails to keep time properly. In addition, applications that are timed by the virtual machine's clock, such as Windows menu animations, may also run slowly. Applications that don't use the timer to delay their execution run at normal speed. Note: Read more...