With Intel's Core 2 Duo and AMD's Athlon 64 64-bit processors becoming widely available, operating systems and user-land applications can now take advantage of the performance upgrade. Linux site Phoronix evaluates the performance of Ubuntu on 32 bit and 64 bit architectures. They arrive at the following conclusion:
Looking over the results 64-bit Ubuntu was able to provide a strong advantage in the GCC benchmarks with both LAME and the Linux 2.6.19 kernel compilation. However, a slight advantage had remained with both Unreal Tournament 2004 and the LAME encoding tests in a 32-bit environment. Outside of the i386 and x86_64 analysis, it is also worth noting that at this time there are no real speed increases between Edgy Eft and Feisty fawn; however, this was only the first Alpha (Herd) release of many to come before the April 2007 release of Ubuntu 7.04.
It will probably take around 3-6 months before Linux can be 64-bit optimized by default. However, it will be up to applications to drive the demand for the underlying operating system to take full advantage of the 64-bit architecture.
The question is — is now the right time to invest in 64-bit processors when 32-bit processors are becoming cheaper? Will better processors become more affordable once applications natively support 64-bit processors?