An update was released earlier today for the PC version of Battlefield 4. Most notable in this update, at least for ATI users, is the addition of Mantle support to the game. Also included are various performance gains for all hardware types, weapon balancing, vehicle balancing, and more.

Changelog for Battlefield 4 (PC) for January 30, 2014
Mantle Support
The new Mantle renderer has been added in Battlefield 4. Most players can expect a performance increase by using this new low-level graphics API.

CPU/GPU performance and monitoringDMR Balance Tweaks
-Increased the damage of all DMRs across all ranges. Specifically, damage has been increased at long ranges to allow three-hit kills against unarmored opponents. Additionally, reduced the penalty to accuracy for sustained DMR fire, allowing more rapid follow up shots in combat. The amount of the damage increase varies from weapon to weapon, according to its intended range, rate of fire, and damage. We will continue to monitor the effectiveness of DMRs in combat, and determine if additional action is needed to make DMRs a viable mid to long range weapon.

Other Items

There were also apparently a number of undocumented changes made in today's patch as well. Some users at Reddit are compiling a list of the items included in the "ninja update" that weren't mentioned in the main changelog from DICE.

Of course, there are some issues with this patch. Many users are reporting that they no longer have any sounds once in a multiplayer map. Players are reporting that while they have sounds for the HUD and background music, all other sounds (gunshots, explosions, footsteps, weapon change sounds, etc.) are simply gone.

Commanders are also reporting now that players with a "killstreak of 1" can be marked as an HVT while in Commander Mode.

Well, at least this time it's two steps forward, one step back.