Intel Turbo Boost

Solution
enable it. it will bump the sped up when only a couple cores are being used. nothing lost by having it on, yet lots gained when it is on :)
The only reason to disable Turbo is when manually overclocking. Since you can't overclock the i5 6500 you should leave it enabled as it is by default. Probably only a Z170 motherboard would even give you the option to disable it.