According to VMware, you'll need AMD64 CPUs that are made using 90nm. That should be the only requirement. I too test my 64-bit OpenBSD guests on a Linux host running CentOS 4.4 (2.6.9-42.0.2.EL kernel). i386 works like a charm. amd64 performs like a VAX.
However, I've tested NetBSD/amd64 (2.0 I think) and that worked just fine. If I remember correctly, the performance problem manifests itself when there is forking involved. If you run CPU intensive jobs (like openssl speed), the performance is fine. If you do a ./configure on a port (which forks processes all the time), it drops to VAX speeds. I'll gladly test any suggestions. Here is output of /proc/cpuinfo from my Linux host: [EMAIL PROTECTED] ~]$ cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 15 model : 47 model name : AMD Athlon(tm) 64 Processor 3200+ stepping : 2 cpu MHz : 1994.273 cache size : 512 KB fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm 3dnowext 3dnow pni bogomips : 3993.80 TLB size : 1088 4K pages clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management: ts fid vid ttp [4] [5]