Trust me, PHP 5.x is going to be one of the first things to go in a few days. Moving to PHP 7 should fix many of our issues in one go -- I hope. Along with a move to nginx (which the rest of our web infrastructure already uses). There's a long story as to why all this hasn't be done previously.
I'll look into changing the caching once we're over the worst of this. Forgive me if I don't want to make significant changes during a massive traffic spike. ;)
(I guess now's a good time to actually register for HN -- we end up on here often enough...)
Hi, Pine64 sysadmin here... yea, our store doesn't like the big surges of traffic we get around product launches. As I speak, we've been getting about 600 concurrent connections for the last 30 minutes, and at least 450 for the last few hours.
We've done some optimization behind the scenes in anticipation, but it's clearly not enough. We're going to be doing some heavy upgrades right after these preorders close.