SAN FRANCISCO—As usual, another opening-day WWDC keynote has brought with it another new version of OS X. The new version, El Capitan, introduces a handful of new features to the platform but is otherwise focused on refinement, both in the overall stability of the OS and in its visual identity (El Capitan switches the system font from Helvetica Neue to the Apple Watch's San Francisco typeface, which changes the look of the OS in subtle but significant ways).

Spotlight becomes "more expressive," according to Apple VP Craig Federighi, gaining some semantic abilities and incorporating some natural language searching. There are also improvements to window management and the built-in apps. On stage, Federighi showed off an improvement to the UI where a shake of the mouse causes the cursor to temporarily grow huge—for finding the cursor when first sitting down to the computer or when waking it up from sleep.

The updated version of Safari shipping with El Capitan introduces the concept of pinned sites to OS X, which will load instantly on starting up Safari and which will remain in persistent tabs in the Safari UI. The browser now allows users to see which tabs are playing music (similar to Chrome), and to mute noisy tabs with a single gesture.

Federighi also showed off some improvements to the full screen and Mission Control functionality (which replaced the older Exposé feature). The new operating system features the ability to work in split screen mode, with application windows pinned to either side of the monitor. You can also create arbitrary "split views," with two windows sharing the screen with a movable divider in between. The functionality appears similar to the pinned application view in Windows, but with a resizable border in the middle.

The new OS also focuses on performance, with Federighi saying that apps launch 1.4 times faster under El Capitan thanks to under-the-hood improvements. Federighi spent a fair amount of time discussing Metal for Mac, a technology that allows direct hardware access to the GPU. Federighi explained that in El Capitan, Metal has been integrated into Core Animation and Core Graphics, with the effect of speeding up 3D performance dramatically—up to "ten times" for 3D gaming, according to Federighi. Metal also helps with pro apps—anything that uses the GPU benefits from the low-overhead access to the GPU hardware.

El Capitan is available today to developers participating in Apple's beta program, and a public beta will start in July. General availability is expected in the fall, likely around September or October.