So, do you want to play the last DOOM at all costs on a crappy laptop like me but can't upgrade your rig at the moment?
If the answers are yes then this guide is for you!
I'll assume you are playing on the lowest graphics and resolution scale

All you need to do to get more FPS is using console launch options
To enable them you have to go on your steam library, click on DOOM, right click, propriety and then click on "set startup options".
Copy and paste all these commands on your launch options for DOOM:

-USEALLAVAILABLECORES -sm4 +set m_smooth 0 +com_skipKeyPressOnLoadScreens 1 +com_skipIntroVideo 1 vt_filter 0 vt_maxAniso 1 jobs_numThreads 4 r_renderapi 0

If you have less than 4 cores on your cpu write 2 instead of 4 on jobs_numThreads

If the FPS are still low you can still do something:

• Try lowering the resolution
  
• Overclock your GPU
  
• Download Memory Booster
  
• Press \ (the button under "esc") and write r_shadowAtlasWidth 32
  Please take note that this command won't work if you put it on the launch options and neither on the configuration file of DOOM, so you'll have to write it every time you start the game

For these guide is everything
The specs i used to test these commands are the following:
-Intel i7 4700mq 2.4 ghz quad core
-8 gb ram ddr3
-nvidia gt 740m 64 bit 2 gb of dedicated vram