the way to get good fps in apex legends is you need at least a amd rx 3600x with ddr4 3000 cl 15 dual channel 16 GB with the bios settings show in in this video;
then my videocard which is a gtx 1060 6GB with windows 10 can get 144 fps for a lot of the game but the videocard is the bottleneck, at 720p lowest video game video settings.
i know a gtx 2060 would let me get 144 fps constantly on the ground if my gtx 1060 is doing this 144 most of the time already, but if you want 1440p then you might need a 2080 from nvidia but if you go to say 1080p maybe the amd 5700xt can do this at 144 fps, but 1440p is maybe too much resolution for 144 fps on a 600 dollar canadian videocard, us i think you can buy a 2080 for around 600, better to buy a 2070 super which is equivalent to a 2080.
and for maximum benefit of the 144 fps copy the settings i used for rivatuner in the video, set the rivatuner to 144 fps and there will be no stutter if your videocard is doing 144 fps all the time on the ground.