Does anyone know if cycles alone is faster in 2.79 compared to 2.78 ?

Not including the denoiser feature, is cycles for 2.79 a direct port of 2.78 ?

Do I get any speed advantage rendering in 2.79 if I am already rendering using cycles for 2.78 ?

Thanks.

Try it ??? Also see release notes for 2.79 : https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.79

You can download and compare it for yourself (.zip files are portable versions, do not need installation):
http://download.blender.org/release/

My guess, no big difference in render time between official 2.78 and 2.79 releases.

But Blender (2.79) from master/buildbot has some improvements in render times, plus the possibility of using GPU + CPU at the same time (16x16 optimal tile size here):
https://builder.blender.org/download

Just that there may be some differences in the resulting image compared with stable versions of Blender, so you should keep that in mind if you already have renders made with Blender 2.78 or 2.79.

CPU and GPU together ? I have to test this.
i always hate my Xeon chips being idle while lol those 2008 models are no match for the two GTX 970s

Yep, it’s a nice feature, but depending on the CPU and GPU (or GPUs) model you have, the CPU contribution may or may not be significant.
Here some clarifications that I had made in the corresponding thread: