Is it? I just downloaded this alpha and ran SunSpider. Chrome 4.0.266.0 got 506.8ms +/- 6.6%, Opera got 763.4ms +/- 4.4%.

Phew maybe you're right I admit I just saw a comment on the opera desktop team blog and haven't tested it myself. However browser benchmarks are tricky - people can get quite different results on different machines...

It might be machine dependent. For me on an AMD Semperon:

Opera 10.5 alpha: 700.8ms +/- 0.8%

Chrome 4.0.266.0: 840.4ms +/- 4.2%

On a Mac book pro and Opera 10.10, I got: 5260.6ms +/- 0.7% I'll try with the new version and report back.

Certainly. Processor, OS, RAM, etc will matter a lot.

FWIW I ran in a Core 2 Duo P9500 with W7 64, 4gb of ram.