Okay with building stations in orbit with over 200 parts but having extreme lag with bases on surfaces of other planets and moons with under 100 parts. (KSP 1.2.2, RSS, RSSVE)

[Masterredlime]

So I'm starting to build outer planetary bases in KSP with a relatively decent computer. I find it weird because I've built lots of stations in orbit in the past and they've presented no problem to my computer with an average fps of around 30+ and these can be stations with over 200 parts. However, when I started landing modules of bases on other planets, once they've exceeded 50 parts, my computer experience extreme unplayable lag that can reach 3 to 4 fps which I find unreasonable given my PC specs and me launching rockets with over 100 parts with no issue. For example, this Europa base of mine can only be played at 4 fps when I'm within 300 meters to all of the modules. 

My PC specs are: Windows 10 Pro 64-bit, Intel Core i7 4790, 16.0GB Dual-Channel DDR3 & GTX 970. If anyone has had similar issues in the past and found a fix for the issue or even the cause of it would be really great, thanks.