1)The first that should be done in a scenario where your system is really slow is to get rid of unwanted programs. There are a lot of programs that run in the background and uses a portion of your resources. These programs can cause a lot of lag in your Windows especially if there are quite a few of them. so turn off background apps from settings and disable startup apps from task manager.

2)keep your window up-to-date

3)update your graphic driver.your computer doesn't natively know how to use all the feature of your video card so,it needs a driver to do that

4)Turn off hardware acceleration

   using discord? using chrome? then you can do this little optimization.This will improve game performance in all games.so, Disable hardware acceleration from settings.

5)Turn on window game mode feature

6) Delete temp files

7)Use high performance power plan

8)Normally it is advisable to use AC adapter while playing games for better performance

-turn off

i)RECORD REPLAYS

ii)record large team replays

iii)RECORD CREATIVE MODE REPLAYS

(THIS IS VERY IMPORTANT TO BOOST YOUR FPS AND PERFORMANCE)

set X-AXIS SENSTIVITY TO 27 TO 30% ONLY (HIGHER CAUSE SCREEN TEARING IF YOU HAVE LOW REFREASHRY RATE DISPLAY)

ALSO SET Y-AXIS SENSTIVITY TO 27 TO 30% ONLY

Targeting senstivity to 60% and scope senstivity to 55%

Pro players always use low dpi and high sensitivity 

-CHANGE SOUND QUALITY TO LOW INSTEAD OF HIGH

FOLLOW THE PATH FROM IMAGE AND LOCATE THESE 4 .EXE FILE

i)RIGHT CLICK ON .EXE FILES ONE BY ONE

ii)GO TO PROPERTIES

iii)GO TO COMPATIBILITY OPTION

iv)CHECK THE DISABLE FULLSCREEN OPTIMIZATION BOX THEN CLICK ON CHANGE HIGH DPI SETTINGS CHECK THE HIGH DPI SCALING OVERRIDE BY APPLICATION BOX

V)OK AND HIT APPLY.

PRESS WINDOW KEY + R TO OPEN RUN

WRITE IN BOX %localappdata% hit ok

Go to FortniteGame>saved>config>windowClient

right click on gameusersettings then properties and un-check the read only box then apply and open gameusersettins config file

i)Find sg.ShadingQuality and set value 0 (by default value is 3)

ii)find bShowGrass and change true to false

iii)find DisplayGamma and set the value 1.000000

now save and close then again right click on gameusersettings go to properties and check read only box again and apply.

PRESS WINDOW KEY + X AND CLICK ON WINDOW POWERSHELL(ADMIN)

PASTE THIS COMMAND AND CLICK ENTER