Maybe, but my gpu is staying at 100% and the cpu isn't always at 100% almost neverIt's kinda strange if the usage of the cpu and gpu stay the same and have those drops. So could be lack of CPU power? GTAV is pretty heavy on CPUs and could be that. Check if it all low do some change. If it don't change you are getting CPU bottleneck.
What do you think about it? He may be bottleneck by the gpu or the cpu at some point. @Fix_that_Glitch