It's not obviously possible to help you with such sparse report, considering you are reporting very different things so, let's try the guesswork and see them, one by one:
keeps crashing midway,
Doesn't normally happen but, if you posted some error report, it would possible to say more.
Note that, a CRASH it's a crash, with some error. If the updated just "quits" to Desktop, it's not a "crash", it's just it has completed all updates and, since after it has completed all updates, it has nothing left to do, it will just quit, without stopping with a useless dialog that would eventually do something useless, like asking your permission to quit, when it really doesn't have any other option than...to quit.
This behavior, of course, has been made intentionally following some users suggestions, that they want to run the FSDT Live Update before each flight, starting it automatically, and that useless confirmation dialog would interfere with an automatic batch procedure. We always add users suggestions, when they make sense.
This, of course, assuming you are not instead getting a real crash, one with some error displayed on screen. Since you haven't said you had any error, I cannot possibly be sure if you were just confused by the normal clean QUIT at the end to be a "crash", or you just forgot to provide the error, so it was a real crash indeed.
A real crash can be caused by many issues but, without an error log, I can't really say so, it's POSSIBLE (even considering your next issue, the program supposedly taking "forever"), it might be caused by either a firewall or an antivirus blocking, interfering or just slowing the update.
So, as first check, be sure the whole Addon Manager folder is added to the Antivirus EXCLUSIONS and no firewall is blocking anything.
takes forever
Under NORMAL conditions, it takes about 6 minutes to install GSX from scratch AND update it:
https://youtu.be/5oHiuDoZB1IThis is with a 1gbit/s connection so, do your calculations if your internet speed is different. For example, on a 100mbit/s connection, it should have taken 60 minutes, with anything in between for other internet speeds.
If your time don't align with this, it might caused by the same reason for the "crashes" (assuming you had real crashes), so apply the same solution as before: antivirus and firewall.
it looks like it is doing nothing
This is the less clear of all. Surely you must see at least some progress bar, even if it "looks like it is doing nothing". If you don't even have anything moving, make a precise report where this happens EXACTLY
