Originally I had all types of media issues in my GoPro HERO4 until I upgraded to these Samsung PRO media cards. They are definitely fast, and i've been using the Samsung 64GB microSDXC in my HERO4 for a few weeks in every framerate and resolution - no issues.
These fast cards are also offered in full size SDHC and SDXC with Up to 90MB/s read speed, 80MB/s write speed. Currently a Black Friday Deal cuts these PRO cards down about 50% OFF via Amazon which ENDS TODAY (find details here).
Samsung PRO SDXC and micro SDXC 64GB / 32GB / 16GB
If you're into the Lexar Brand Name, there is up to 60% OFF normal retail price on various CF, SDXC, and Flash Media found over at B&H (click here).
Lexar Compact Flash, SDXC, microSDXC, Flash Media