Very random FPS droplet (or spike ?)

Hey there i have a problem that for some reason i just never botherd to ask about earlier but.

I do gmod animations and machinima and even now that ive upgraded my comp i have this issue .Heres the specs :

Processor Intel® Core™ i5-6600K CPU @ 3.50GHz
Manufacturer Intel
Speed 3.5 GHz
Number of Cores 4
Video Card NVIDIA GeForce GTX 970
Dedicated Memory 4096 MB
Total Memory 4.0 GB
Memory 16 GB

And i do have a lot of models downloaded n such always ready just in case , but seeing how my computer can run GTA 5 perfectly , i am sort of suprised this is happening still . Its not like a huge drop or spike but its like every 15-20 seconds (it varies) if i keep moveing around no matter how simple the map i get this less then maybe a second stutter or whatever and it just really annoying especially when im tryign to pose and even worse when im filming or something. I did look into this but a lot of the responses are about serious fps drops or spikes so i figured i might as well ask .

What about your hard drive? Anti-virus software could cause spikes in that regard. I know I’ve had that happen before but I can’t remember at all why. Is it happening in every server, or just your local server?