If your saving files to the same SSD as your operating system, make sure there is plenty of room as it will slow everything down, especially with auto save set to 5 minutes. I save all my files to a separate SSD and backed up to an HDD. Never have issues with SU speed.
The Quadro series are known to be not worth the money when it comes to Sketchup.
Equivalent approximately to the older GeForce GTX 1650 “consumer” card, found in “entry-level” gaming laptops.
I don’t know of any modern 3D/BIM/CAD application that wouldn’t work quite as well with an equivalent, cheaper, “consumer” Nvidia card.
Quadro cards are usually found in “workstation” computers meant for corporate buyers. I really see no reason why Lenovo, HP, Dell and a couple of others like that still keep putting them in their offerings.
Hi
I dont know if anyone mentioned, especially with a model of this size, you MUST not leave any open surfaces and group large ones on their own tags and hide them. This is important on large models.
Also if not mentioned, windows update sometimes causes problems that doesn’t get fixed until next sketchup update. ive learned this over the years!
As a matter of fact im all of the sudden running into this again. I am planning on upgrading to an RTX and add 16 gig more of ram on my system. But every so often this issue comes up. and I really think its windows updates issue most of the time. Looks like DaveR covered the surfaces and unnecessary objects and is ABSOLUTELY right! even if you are running a powerful system , Sketchup doesn’t care! this does not prevent Sketchup from trying to process everything it can when its NOT told to. We inexperienced modelers run into this all the time!
Look at this surface that I applied a “Detail” to. I just grouped this and Sketchup is running exponentially faster.
I know this is an older thread, i had a comment typed up back in 2019 but never sent… I upgraded my PC then and hoped it would fix the slow down, but it didn’t. Got busy with life and never got back to it… Here i am in 2022 finishing what I had and it is so sadly slow it makes you want to cry. Especially with another upgrade where im running z590 chipset, i9-11900K cpu and it is water cooled with RTX 3060 xc 12gb. Has several NVME drives the primary one is a pci 4 stupid fast samsung evo 980 2tb pro. This is so slow i can take a drink of my cofee and sit there for a few to swallow and then i can finally resume. Sad thing is i dont have much even on the board. Making a mold for strain relief by using hot glue injection… Maybe 50mm x 60mm work space and nothing complex.
Not even mentioning the crashes. Going to use web base is a joke, half the tools are missing and cant move things around like you can on desktop version… Just sad. 123d it is or autodesk fusion 360 
Your profile states you are running Win11. SketchUp 2017 and 2018 do not support win 11. What are the statistics from your model, from model info?
Make sure you have profile edges and hidden geometry off. Profile edges usually is the cause that most don’t realize slows things down, even if you are running an RTX3090.