@GTR12: No, because I need to RD into my work machine while on the road or at a hotel.

Just spit-balling here, but based on my prior experience I'd offer 2 suggestions:

1.) It's a connector issue. Either with the port the video card is plugged into on the mobo, or one of the power connectors going from the PSU to the video card. The GPU needs power, isn't getting it consistently, and the frame rate stutters as a result. (Did you try swapping out power cables from the PSU to the GPU? Or checking the soldering of the power cable ports on the GPU to make sure they're intact?)

2.) It's a lag issue. This used to happen to me when I played SWTOR. In random areas, the FPS would dip as a direct result of server lag. Some forum posts attributed it to a memory leak but I could never substantiate that. Considering Rocket League is an online game, it's possible there's a lagging player or the server, and the game engine responds with an FPS dip while it attempts to sync things up.

Looking to buy a new laptop. 15" with some muscle for games (XCOM 2, Skyrim, Division) with a 970m, an SSD, and 16gb of RAM. But I'll also be using it for work. And that's my dilemma.

I need to remote desktop into my iMac at work, which has a 4k display. RD'ing into it on a 1080p display makes things look terrible, small and generally hard to read. So I was contemplating getting a laptop with a 4k screen.

The challenge with that is running games at 1080p, I've heard they will look blurry on a 4k screen. And at a $1500 budget, I doubt I could get a 4k laptop with enough GPU power to actually run those games at native res. (Altho I do get a decent corporate discount from Dell / Alienware.)

So... any advice from people who have a 4k laptop screen but run games at 1080p? Is it that terrible? Could I run my games at 1440 or 2560 and still get decent frames?

Not denying the game is fun or anything (as I haven't played it). But everything from the logo to the screen shots, artistic style, even the armor and weapons I'm seeing in the screens and videos for this game make it look like they are aping WoW. 

This issue needs more attention in the gaming media. Pretty sneaky on Ubisoft's part. They need to release a patch to fix this. I didn't spend $50 on a game to get a gimped version, especially when their own sales and marketing details showed the PS3 version as having 5.1, just like the 360 version. If I had known it didn't, I'd have bought the 360 version. A bit pissed about this.