@Suzezaazknown issue - Apex code is just badly optimized, everyone knows that, noone officially admits that.
I run Radeon 5700 XT which can't handle stable 143 FPS while I max out well above 200, latest average per gaming session is ~220 fps, yet in some places (dropship, looking into loot bins, some random places on maps) FPS drop to 90 or even below.
I have made a thread about it, there was no reply from EA/Respawn side, in the meantime reddit is full of similar cases, you can google it based on your GPU and read more details.
My suggestion to you (what helpped me):
1. uncap FPS - I was told when I came to the game to cap FPS = monitor refresh rate, yet it created actually more glitches, shutters. Plus it is said that the higher the FPS the lower input lags = basically you benefit in cases when you take a fight in an area where game pushes higher FPS than your refresh rate
2. disable all synchronization - disable V/G-sync, run game via advanced option = -forcenovsync
3. depending on your GPU turn down graphics settings e.g. if you see that your max fps are still below the monitor's refresh rate, turn down the setting in-game called streaming budget aka VRAM to a level where you at least in most places on the map are pushing the equivalent of monitor's refresh rate be it 143, 60 or 240 FPS
4. check hardware usage - Apex is also known to be very CPU demanding game, might be the case that you are bottlenecking not at GPU but CPU side. Some have said to me that actually upgrading CPU helped them push more FPS in-game. Usually this can be done via various in-game overlays provided by CPU/GPU manufacturer or 3rd party software e.g. https://www.msi.com/Landing/afterburner/graphics-cards
Hope it helps!
