Honestly I'd give it another try at some point, perhaps with the player base slowly declining It is also helping. Let's not forget how much of an awful launch the online was, despite GTA 5 selling record amounts.
It must of got better in the last 12 months. It left a bitter taste in my mouth to try it again.
I'm really not sure as I've completed all heists etc before without an issue.
SSD is irrelevant, I haven't used a spinning disk since 2010 (on a 970 NVME now). During online games, you used to get stuck 'in the clouds' for minutes at a time and sometimes get passed back to offline mode. This is a result of using P2P server instead of dedicated hosts. This was a well known problem with people reporting it as often as the cheaters on the platform. The most frustrating game mode to play was heiests with people rage quitting when getting stuck in the clouds causing the team to alot get sent to the clouds only to have to find a new team member and waiting all over again.