So I got a 512mb SSD external drive yesterday and moved some games over. I went with the longer loading games. Results were mixed, I'll list the games I put on it and what diff it made:
AC Odyssey Metro Exodus Wasteland 3 Had no real difference in load times or anything else.
Every other game had some sort of improvement, some larger than others.
Control loads a good bit faster, I'd reckon by at least half. I haven't played enough of it to gauge any difference in performance/Menu selection as it was lightning fast. (that's about to change tho cos had a blast)
Sea of Thieves has a pretty big improvement, load time is about a quarter of what it is on a normal HDD and then in game, the island LOD loads in from much further out.
PUBG also has a huge improvement, the potatoe buildings are all gone as they just all load in, getting into a game is also really fast. It felt smoother but I'm not sure if it was any diff cos it runs well enough these days anyway.
Minecraft Loads a lot faster.
DayZ Loads a lot faster and, more importantly, it removes the stutter completely. Now I haven't gone to the worst effected areas but it's a pretty big improvement already.
The Witcher 3 Loads again VERY fast and going to UI/Menu is lightning quick
The Outer Worlds is massively improved, load times are far less and that unreal lod load up at start was barely a second.
Skyrims difference is absurd, from Whiterun to outside world was about 2 seconds!
State of Decay 2 probably had the biggest improvement, apart from the load times being far less, the game actually ran A LOT better, I don't know why but it really did.
Greedfall was again lightning fast to load.
I'm probably gonna change out the 3 that didn't have any improvement and try RDR2 (which is about the size of all 3 combined) and Dishonored 2 which has a long load.
Also of note, when I brought up the guide while in any of these games on SSD it was instant, like it worked fine anyway but it was definitely faster.