On the heels of Tuesday’s release of 64-bit Chrome for Windows, all Mac Chrome users on the beta channel will be updated to a new 64-bit version of Chrome 38. Previously, Chrome was a 32-bit app on Macs. While doubling the number of bits won’t make things twice as good, it does allow us to make a number of speed and security improvements.

64-bit Chrome has become faster as a result of having access to a superior instruction set, more registers, and a more efficient function calling convention. Improved opportunities for ASLR enhance this version’s security. Another major benefit of this change comes from the fact that most programs on a modern Mac are already 64-bit apps. In cases where Chrome was the last remaining 32-bit app, there were launch-time and memory-footprint penalties as 32-bit copies of all of the system libraries needed to be loaded to support Chrome. Now that Chrome’s a 64-bit app too, we expect you’ll find that it launches more quickly and that overall system memory use decreases.

Because of this change, Chrome for Mac will no longer support 32-bit NPAPI plugins, although their 64-bit counterparts are supported. Users shouldn’t notice any changes, because most major plugins are available in both 32-bit and 64-bit form, and many major websites have been switching from NPAPI towards more modern HTML5 APIs. This is also a good time to remind everyone that NPAPI support will be removed from Chrome later this year.

Nearly every Mac user has a computer capable of running this 64-bit version, so we’re automatically updating all Mac Chrome beta channel users. Those few users with first-generation Intel Macs will miss out on the fun, but as we bid them farewell, we’ll remind them that they’ll still be able to run the latest version on the stable channel, Chrome 37.

You can check to see if the Chrome you’re running is a 64-bit version by checking Chrome’s About page (chrome://help) and looking next to the version number. If it says “64-bit” there, that’s a sure sign that you’re running one of these new builds. We hope that this is the only visible difference that you’ll find between the old 32-bit and new 64-bit versions, but in case you find anything amiss during the beta period, please let us know.

Posted by Mark Mentovai, Software Engineer and Register Doubler