From the developer Gordon Freeman.

From Dev GordonFreeman

Here are some convars run new GFX features at lowest possible settings -

bms.exe -console -vsync 0 +fps_max 999 +net_graph 1 +cl_csm_enabled 0 +cl_csm_qualitymode 0 +nr_shadow_active 0 +nr_shadow_quality 0 +nr_shadow_res 4 +nr_shadow_filter_quality 0 +nr_shadow_max_dynamic_passes_per_frame 0 +nr_lights_quality 0 +np_gr_active 0 + np_gr_quality 0 +np_FPS_Indicator_enabled 0 +nr_gbuffer_for_secondary_cams_enabled 0


+nr_lights_quality 0 VerLow 1Low ( Use 1 or Low mode incase you see a lot of flickering with VeryLow )

You can also experiment with nr_debug_cull_deferred_lights 0/1

You can further squeeze out more fps by lowering your resolution.

Edit - For old Source Engine settings there are gazzillion guides out there.
You can experiment with new borderless and fullscreen mode in our engine.

Edit #2 - Any changes to settings related to new GFX features take effect only when you reload the map or restart the game. I would recommend adding above convars in a config file or to launch options if you have a Low End PC.
Adding above convars to launch options or config file helps game detect disabled features at launch time which in turn can lead to VRAM consumption (sometimes) .

We can also make a autoexec to test things more modular.

Going to

C:\Program Files (x86)\Steam\steamapps\common\Black Mesa\bms\cfg

we can modify autoexec.cfg or load our own cfg (i called mine lowendligth.cfg)

in autoexec, we put
exec config.cfg
exec lowendligth.cfg
//exec threading.cfg

Create a new notepad, and put those commands

https://drive.google.com/open?id=1ICfQCFa9OsjeQer_cH1DrQ490KJkkY87

saves as "lowendligth.cfg" and save it on C:\Program Files (x86)\Steam\steamapps\common\Black Mesa\bms\cfg