We use snort on alot of servers, no issues that we can see
Steven Ciaburri | Industry's Best Server Management- Rack911.com
Software Auditing - 400+ Vulnerabilities Found - Quote @ https://www.RACK911Labs.com Fully Managed Dedicated Servers (Las Vegas, New York City, & Amsterdam) (AS62710)
FreeBSD & Linux Server Management, Security Auditing, Server Optimization, PCI Compliance
I use snort but run it on dedicated machines. A sun ultra 5 can handle snort with no problems so I doubt you would have any cpu utilization issues with a newer x86 cpu unless your server is already under a constant heavy load.