Linux Kernel 3.12 in its stable release has been made available recently which comes with new features and optimizations. Here are some of them taken from Phoronix:

- Improved Dynamic Power Management support for newer Radeon GPUs and other changes after the Radeon DPM feature was merged in Linux 3.11 
- A Snapdragon KMS/DRM driver from the Freedreno project for the Qualcomm Adreno. 
- Runtime GPU power management for NVIDIA Optimus laptops to be able to dynamically power on/off secondary GPUs. 
- Experimental support for DRM render nodes. 
- AMD Berlin APU support for the first HSA server APU. 
- Intel Haswell graphics improvements with eLLC DRAM support now enabled for the systems with Iris Pro 5200 graphics bearing dedicated memory for graphics. 
- Staging driver updates. 
- Sound driver work. 
- EXT4 gained new features of aggressive extent caching and better recovery. 
- F2FS file-system improvements. 
- Lenovo Ideapad Slidebar support. 
- XFS file-system improvements. 
- Btrfs file-system performance improvements.

Kernel 3.12 Installation

To install kernel 3.12 in Ubuntu/Linux Mint, enter these commands:

cd /tmp  
wget -O kernel-3.12 
chmod +x kernel-3.12 
sudo sh kernel-3.12 
sudo reboot

To uninstall kernel 3.12, run this command:

sudo apt-get purge linux-image-3.12*