Here's what we're looking at -- a snapshot of a High FPS period and a Low FPS period during your gameplay - it's the same whether 27-33 FPS or 60-75+ FPS:
What we can observe is that GPU and CPU temperature and load are well within margin in both High/Low FPS periods, but the GPU Boost Clock state is flipping between On/Off when it should be constantly pinned in the Boost Clock during 3D gameplay.
Basically, your gfx card is not performing as expected, and it's thermals look well within range. The current driver version for the GTX 1060 is 442.59, and was released 5 days ago on March 10th.
TL;DNR
There are plenty of other issues to consider, and to troubleshoot -
but the very first step would be to use the most recent driver versions for your GFX card. On top of that, installing the latest updates for your Windows system is a wise starting point, too.
You can download the GeForce 10-Series drivers manually from their website:
https://www.geforce.com/drivers
OR - If you are not technically minded, you can install the GeForce Experience software to help guide you through the process to perform a clean installation of this new driver (wiping old settings and driver). You will need to then re-configure your GFX settings, so before doing this, you could screenshot your 3D Settings if you want (not the screens you shared, those are just display settings in the nVidia Control Panel, you want to screenshot 3D Settings - this page:
https://imgur.com/RcjR7XF )
(
pro tip: if you want to use GeForce Experience to manage driver installation, but don't want their wanna-be SteamStore app running all the time, you can literally uninstall it directly after using it with no issues to the nVidia Control panel or drivers)
**edit: if you have V-Sync turned on, try turning it off and see if that fixes it - there are others with this issue and some of the suggestions are completely unfounded but v-sync seems a possible culprit - google around a bit for '1060 not staying in boost mode during 3D gameplay'
