Photoshop CC 2014 is MUCH slower than Photoshop CC in a side-by-side comparison.

I think it could be system-specific.  I did a very careful comparison some days ago and found the new version a little faster myself.  But I'm on the PC side (I have a reasonably powerful PC workstation).

Just because you mentioned specific things, I tested again.  I have a really deep, huge test image with lots of groups, layers, colors, etc. that someone prepared as a layer operations torture test.  Here's what I found:

• Opening this document, 1.65 GB in size and 8000 x 8000 pixels, took 29.6 seconds in Photoshop CC 14.x and 21.6 seconds in Photoshop CC (2014).
  
• The time to select a layer is small enough that it's nearly impossible to measure accurately.  For example if I select a Curves layer the Properties panel is updated nearly instantly, and the highlight in the Layers panel shows up maybe 0.2 to 0.4 second later (the histogram fills in ever so slightly after).  How are you measuring the time to select layers, specifically?  Subjectively it seems that Photoshop CC (2014) is slightly more responsive if anything with regard to selecting layers.
  
• In Photoshop CC 14.x hiding the "white dots" or "black dots" layer groups in my test image takes 1.8 seconds.  Showing the same layer takes 2.0 seconds.  In Photoshop CC (2014) the timing is consistently 0.2 second less at 1.6 and 1.8 seconds.  I measured these operations a lot of times with a 0.2 second resolution stopwatch to make sure I got solid numbers.
  
• I selected the top layer and created a closed path shape with the Pen Tool.  I then zoomed in to 2500% and selected one of the points with the Direct Selection Tool, then used the arrow keys on the keyboard to move it a pixel.  It took 0.8 second to update the display in Photoshop CC 14.x, and 0.6 second in Photoshop CC (2014).

-Noel