client/server gpu and cpu question

Ok here is the deal.i have 2 laptops(for gaming yeah i know) the more poweefull one which i use runs the server which i play in.(2 player start game not a dedicated server)
The other one joins to play
I used the weaker one for myself untill i bought this better one.althought lag was never present on either computer.the new one can take dubble the amount of NPC and/or props.however if the lag is due to NPCs the stronger one lags and the client doesnt.so NPCs use the cpu.however props lag both laptops.i want to know
Do gmod physics get calculated through the GPU or the CPU.and does the server calculate ALL physics and the client only recieves them asking because the gpu difference in both laptops is huge
Client:Intel Core i3 2.4 ghz dual core 4 gigs ddr3 ram and a intel hd integrated graphics with 256 mb vram(ripped from the main pc ram) and a 1366p display
The “server” or more accurately the host is
8 gigs of ddr4 ram 2.5ghz dual core intel i5 with turbo boost to 3.1ghz a nvidia GTX 940MD 2 gigs of dedicated ram and a 1920p display. Both laptops run linux mint .the weaker one had windows and saw a great boost after being forced to linux due to windows giving me driver problems.so the host runs linux too.using 596 addons
I want to know because the client pc is set its resolution at 780p and lowered everything.making some models and any signs or overlays outside health and ammo pixelated and unreadable and unusable.i had managed to play on higher settinfa before but not sure if the vast amount of props will make it lag.any ideas?
EDIT: with our current settings playing is perfectly ok.both laptops top over 40-80 fps depending on map and we can spawn in a solid 30 combine.50 zombies or over 100 VJ npcs.but the Scars interface is all pixelated and unusable and some trees or models are litteraly pixels.making roleplay less enjoyable

GMod physics uses the CPU shared (client and server). Intel integrated graphics isn’t supported by any Source game, and falls below the minimum requirements. Your lag issues most likely stem from your large amount of NPCs and addons.

The game doesnt lag at all unless overloaded.i can confirm the client has only a integrated gpu and has been capable of more than playable performance independent if it ran on windows or linux.so physics get calculated by both machines.the cpu never gave the client trubble.and because the gpu seems to be utilized only for effects i will raise the graphics to a level where the Scars interface is readable.thanks!

Your only solution here is to really upgrade your hardware. You’ve already said it yourself, many props will make it lag.

You could try gmod_mcore_test 1, but I doubt it will benefit much on a dual core.