I am having the same issue, tried the following with no success.
- Updated Windows
- Completely removed all addons
- Uninstalled all Nvidia Drivers and re-installed
- Re-Installed WoW
- Edited most recommended settings in graphics options based on past posts
I have a GTX 1080ti and Intel i5 6600K
Still the game will freeze for 5 - 30 seconds and GPU usage spikes to 100%. On some occasions it completely crashed game. Worst in new zones as well as when more people are around.