You did not see or probably missed it, but I did say a few patches ago it worked good enough to play! SOMETHING has changed! It is the map it is broken and needs to be tweeked! My system is more than able to handle this game (it is a desk top system by the way don’t know why people are saying mobile card?) and the newer ones, it is something in the coding/graphics and they know it, as it was mentioned (by UV) that they intend to address it… So relax, I have hope they will tone it down and fix it. I get they want to make it pretty but something is messed up in the process. As I said before I run games at full graphics settings without issues and they are MUCH more graphically challenging then this game, in fact they make this look like crayon painting in comparison, so it is the map, it really is that simple!
Their graphics system is called “Metal”, before that they use OpenGL like Unix/Linux.
But I assume that shouldn’t matter, because the game runs on unity, a game engine, and this manages mostly if not all of the graphics for the game on the computer. AFAIK the devs creating objects, materials, animations, logic etc in an abstracted way for this engine and not directly by programming the system graphics API like DirextX, Metal or OpenGL.
I have an RTX 2080 and get a significant amount of lag on Synedrion maps only. Certainly something wonky with something on these maps that’s causing a wide variety of problems for a wide variety of people.
Mostly whenever I watch a Heavy jump or launch grenades/rockets across the map (zooming out) which isn’t as problematic on other maps.
I can confirm that heavies using jetpack , that animation is causing lag.
On Synedrion maps or also elsewhere? Interesting as I haven’t experienced any lags with my GTX 1060.
Edit. I take it back… Tentacle retaliation is in REAL slow motion every time it kicks in.
I will check tomorrow, actually today, 1am here 
Synedron map, Heavy and jet pack:
looks ok for me
A bit of lag and artifacts, due to glass reflections on the map, I guess
but I have a Ryzen 7 3800x and Nvidia RTX 2070 Super:
If I could get this performance I would be over the moon… This looks fine! Mine is like a flip book and it does its own thing when you select an option like grande, you pick it and it throws it straight away in some random direction usually at your own men!
For comparison, DoA map
It’s not the heavy animation. Frames go down if zoomed out. Heavy jump just so happens to zoom out and slowly pan the camera to make the frame loss obvious.
After watching 3 long videos of a Heavy using the Jetpack ability, I find myself praying that they one day hasten the animation. I could write a book on The Impracticality of Jet Packs before that guy lands. 
I have to say I’ve noticed the frame rate drop on Synedrion missions too, mainly when it goes into over-the-shoulder aiming. I have an older i7-4790K and a GeForce 1070, which along with 16GB of good ol’ DDR3 run most games fine, on near max levels. I think this is case of optimisation - the way the glass is working is causing it.
I haven’t seen transparency effects cause such an issue since I tried to play Dark Forces 2 without a 3DFX card! 
What about Hal-Life 2 with transparent glass and water?