Read the numbers again. WIFI surfing time increases by 16 minutes. The only scenario runtime that decreases is the load test, which makes sense given that the Broadwell system uses more power at full load. However, you need to consider that the Broadwell system also performs better at full load than the Haswell system. In particular, at full load the Broadwell system maintains max turbo of 2.7 ghz for the CPU and 900mhz for the GPU. The Haswell system throttles the CPU down to 1.4 ghz, with the GPU at 1 ghz.
To me, it seems that the improvements in Broadwell are somewhat hidden by the clever design of Haswell (benchmarks are short enough to run at full turbo in Haswell, even if it cannot sustain that performance). Whether due to an inability to raise clocks in Broadwell or due to a desire to maintain product segmentation, Intel did not raise the turbo in Broadwell. This means that in most benchmarks you'll only see the nominal 5% IPC gain.
Perhaps, raising the turbo requires architectural changes designed for the 14nm process. Thus, you may see bigger jumps in benchmarks numbers with Skylake.