By default, a dynamips instance will take 100% of the host CPU. To avoid this, please read the "idle-pc" section in the README file (${PREFIX}/share/doc/dynamips/README). The configuration generator "dynagen" (available separately) can help find a good value. You can greatly reduce startup times by uncompressing your IOS images with unzip. N.B. The just-in-time compiler, required for good performance, is currently only supported on i386 and amd64.