Ever since the new patch, whenever I first launch the game and enter, I get a crazy amount of lag, regardless of where I am or how many people might be in that instance or if I'm in space or the ground. It's not until I change and load a new location that the problem fixes itself.
This only happens when I first enter the game, once I load a new location, the problem goes away for the rest of my game session. It's quite annoying since I have to now plan ahead whenever I disconnect from the game since I need to be near a planet or star base in which I can beam down to, otherwise I'll have to deal with nearly unplayable lag until I can find something which will take me out of the instance I'm in.
I too had major lag post-Season 8, but not only on startup. My solution (Intel graphics) ended up being to switch from DX11 to DX9 ex, and manually set video memory to the highest, not 'Auto'. Probably not relevant to you, but just sharing information.