gtx 1060 discrete functioning apex legends

It's the map optimization. even high end systems drop frames.. limiting your frames a bit below your maximum with rivaturner makes it a bit more stable as these dips are not as steep but thats about it. i drop from 140-160 to 80fps when entering capital from epicenter so your's is just the same but with lower end system. around 50fps drops.

I would also not recommend trying to go as deep as changing your thermal paste.

You can reduce some excess load in your apex legends by opening 

Videoconfic.exe at Respawn>apex>local

Open it with text editor and change "setting.csm_enabled" "1" to "setting.csm_enabled" "0"

then save the text file and right click the videoconfic, go to properties and set it to read only so apex wont reset this when you play.. it will disable shadows from the game reducing your load quite a bit.

CPU clock will periodically drop while gaming due to the motherboard VRMs overheating causing your GPU usage and framerates to drop. Monitor your CPU clockspeed while gaming, if you see the CPU clockspeed drop while in game, but your CPU temps are fine, it's probably VRM throttling. Undervolting will help with this issue to some extent or just taking off your overclock