Steve Herrod, Vice President of Technology Development at VMware, from its blog details how much ESX Server 3.0 is more performant than its predecessor:
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First, we’ve sped up memory management unit (MMU) operations inside virtual machines. In particular, we’ve decreased latencies of key operations such as page faults and context switches. This benefits almost every workload, and in particular process-heavy ones such as Terminal Services, Databases, and many enterprise applications. Such applications often require large amounts of memory, and virtual machines can now use up to 16 GB of memory by enabling Physical Address Extensions (PAE) within the guest operating system.In ESX 3.0 we improved PAE performance so that there is negligible overhead when running with PAE enabled. We’ve also added a number of optimizations to improve the performance of applications on Linux guests. In particular, we’ve optimized our handling of the Linux Native Posix Thread Library (NPTL).
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While the single VM performance improvements focused on CPU and memory, we have also made a number of improvements to I/O performance. We’ve optimized our guest virtual Ethernet adapter (vmxnet), improved VM to VM networking and re-architected our networking layer for ESX 3.0. This helps workloads such as multi-tiered applications and web servers. On the storage side, we’ve introduced VMFS3: a new, more scalable, distributed file system that includes enhanced file locking and improved caching to support large numbers of VMs. For the new storage options (NFS and iSCSI) we worked to ensure that the performance is up to the standard that our customers have come to expect…
It’s worth to read the whole article.