It's got nothing to do with the graphics settings. There are no more details to give, as no error dumps are recorded.. the game just exits.

I refer to the second-to-last paragraph in my original post.

Edit: I am now re-installing to see if that'll help.

Ive used steam for a good few years and now and what you explain as happened is normal. Its steam checking for an update after the game closes or, depending on the game, syncing it with addons etc. For instance, if you have skyrim on steam, if you exit out of that and quickly look at the library, it looks like steam is going to update skyrim when it is actually just checking for patches and syncing addons.

But I too get the constant crashes in sins. I do enjoy playing it but I mean quite literally when I am unable to play it. Same thing with about 4 friends who got the game with me, we can't get on it for more then 10-20 minutes before the game just closes out or runtimes.

I just finished playing a huge random single-star map with me and 9 hard AI FFA. After about 2 hours of play, I took a screenshot with steam, and attempted to view it while in-game, and it crashed due to a C++ runtime error. 

(The next ones are probably unrelated.) 

Later, about every 30-45 minutes or so the game would just go black screen and then exit to desktop. No error message was given, and all mini-dump files are 0kb in size and contain no data. A number of them, at least, happened RIGHT AFTER and autosave had occurred, which was convenient, but might also be the cause.

 My graphical settings were the defaults, except the resolution is 1920x1080. graphics card is Nvidia GForce GT 330 M (laptop) and I have current drivers. I haven't tried reinstalling it, yet, but I kind of doubt it will help.

I suppose it could be due to it capping out its memory, since it's a 32-bit game and there were lots of ships milling about (I was vasari loyalists with maxed fleet and cap ships).

What are system specs?

The LAA wont do you any good really, I let Stant handle the why if it comes to it.

Are you doing a few steps to as a player to reduce the lag? Like trimming your Empire Tree? Turning off Trade Ship Icons? Turning down the graphics and other graphical effects(planet elevators etc etc)

You can even go as far as modding the game to reduce the amount of Trade/Refinery Ships spawned, and reducing Strikecraft per squad.

With these suggestions, some have seen vast improvement to the eventual end game lag. While some have not. 

Another suggestion is to watch what programs are running in the background, setting an affinity to one of your CPU cores for the game only, setting the rest of you backgrounds programs to the rest.

Core i7 @ 4.4 Ghz.
16GB of memory
SSD

Tweaking graphical settings had no effect what-so-ever. It started happening as soon as the map was loaded. Clearly the LAA did something, as the game has been stable since.

The problem even persisted after a re-install of the game. The strike craft reductions you mention were part of TSOP and AFAIK they have more or less been implemented in to the main game?

70% of the available memory is there for Sins.. that should be enough for any game.

I smell Khan.

A dumb thing to do?

I changed settings, restarted, issues persisted.

I changed settings back, restarted, issues persisted.

I tweaked the .exe, problems disappeared and the game is only using 1.7GB of memory at any given time, almost 1.8.

Regardless, I just want to play the game - it's not like what I did is irreversible or anything, but maybe others had experienced a similar issue so I figured I'd report it.

Steam has never caused me any issues, what-so-ever in any game at all. The only issues I've seen from using steam have been due to developers, like Ubisoft, imposing massive DRM measures and you can't really fault Steam for that.