I recently just installed the latest version of GNS3 (v1.2.3) onto a Windows 7 VM for Cisco Adapative Security Appliance (ASA) testing, as there is usually some work required to get a Cisco ASA working in GNS3 I referred back to my older post http://blog.ryanbetts.co.uk/2014/06/emulating-cisco-asa-firewall-in-gns3.html to remind myself of the configuration and QEMU syntax. After I got used to the new GUI and made the configuration changes when I tried to launch an ASA instance it failed with "Server error [-3200] from 127.0.0.1:8000: ASA-1: cpulimit could not be found, please install it or deactive CPU throttling".
To fix, click Edit and then Preferences...
Expand QEMU and then QEMU VM's, highlight the QEMU VM in question and click Edit.
Click on the Advanced Settings tab and untick the Active CPU Throttling option. Click OK and then Apply.
You should now be able to launch instances of the ASA firewall inside GNS3 v1.2.3.