Ok so my FPS used to be awful like 15, but i got a gtx 1060 and it's gone up to like 45-60 sometimes, what other part(s) would I update to get better FPS. Like I haven't updated anything else so the rest is BOG standard.
Better CPU, you'd be suprised on how much they can bottleneck
You'd also want enough and fast ram and putting your games on an ssd can improve loading times which means your gpu/cpu isnt busy with loading more of your map all the time.
Also overclocking will also get you some extra performance.
For gmod you'd really want a cpu with good single core performance(source engine lul) and a decent clock speed
Your GPU will do jack shit in Garry's Mod, my RX580 just floats around 17%-40% usage while my Ryzen 5 1600 does all the work as Source is CPU bound. Garry's Mod isn't all too restricted to single core performance anymore thanks to gmod_mcore_test so just get a good CPU with a good amount of single and multi threaded performance for your motherboard to get the most of your moolah (if you go Ryzen then having fast memory is a good plus as it will benefit from it). Be like me and play with r_3dsky 0 r_shadows 0 r_drawdetailprops 0 and you will have above 60fps in city and 30 in bazaar depending how busy those locations are.
Don't put Garry's Mod on a SSD unless you really cannot bare loading times and want to fill it up with demos faster than Exrobite can rack up bans.