Ubuntu 15.04 Brings Some Graphics Performance Improvements For Intel Haswell
There wasn't much change out of the demanding Unigine benchmarks.
Warsow was flatlined for the HD Graphics 4600 between Ubuntu 14.10 and 15.04.
Xonotic also didn't have much to get excited about, with the Intel Broadwell numbers being much more interesting as it's a newer platform still maturing on Intel's open-source driver stack.