Hi All, I should write a blog post on this, but I can't wait... In recent days I've written a script to build a Cog VMMaker image from Squeak 4.5. See http://www.squeakvm.org/svn/squeak/branches/Cog/image. This has allowed me to run the current Cog VM against Spur side-to-side. To build a Cog VMMaker image on my 2.2GHz Intel Core i7 MacBook Pro using the current Cog VM takes about 2 and a half minutes: McStalker.image$ time oscfvm CogVMMaker.image BuildSqueak45Image.st real 2m30.671s user 2m15.683s sys 0m5.283s To build the equivalent image using Spur takes about 1 and a half minutes: McStalker.image$ time spurcfvm CogVMMaker-spur.image BuildSqueak45Image.st real 1m34.943s user 1m23.666s sys 0m6.810s Comparing: 94.943 - 150.671 / 150.671 * 100 -36.99 83.666 - 135.681 / 135.681 * 100 -38.34 150.671 / 94.943 1.59 135.681 / 83.666 1.62 that's about a -37% speedup, or 1.6x faster. -- best, Eliot