VmwAROS experience will change depending on the host operating system: VmwAROS allocates a minimum of 128 MB of RAM, plus the amount needed by VMware to work. A computer with 1 GB of RAM will be dramatically faster than one with 256 MB. A 1,5 GHz+ Pentium4-class computer is warmly recommended, due to emulation times. Please don't forget VmwAROS isn't running directly on your PC, but on a emulated one on top of it.
Any antivirus, firewall and generally anti-malware software preloaded in memory, running on the host operating system may slow-down VMware: if you're using VmwAROS only on that machine, please close temporarily such kind of programs. Using eMule will decrease networking performances.