Apple today seeded the fourth beta of OS X 10.10.4 to developers, just over two weeks after releasing the third OS X 10.10.4 beta and a month after releasing the first OS X 10.10.4 beta. OS X 10.10.4 has been in testing since mid April, following the early April release of OS X 10.10.3 with the new Photos for OS X app.

The new beta, build 14E26a, can be downloaded through the Software Update mechanism in the Mac App Store or through the Mac Developer Center.

OS X 10.10.3 brought several consumer-facing changes including the new Photos for OS X app, a redesigned emoji picker, and diversified emoji, but OS X 10.10.4 appears to be an under-the-hood update that brings performance enhancements and bug fixes. Thus far, OS X 10.10.4 betas have not included outward facing design changes or feature additions.

The first two updates to OS X Yosemite, OS X 10.10.1 and OS X 10.10.2, were also minor behind-the-scenes updates that improved performance through bug fixes and enhancements.