[zodvik]

I wrote a lot of code for payments processing at an Indian e-commerce shop & see/make it scale from 100s of QPS to ~200k QPS. Just having the code paths exercised by so many people over a day gives me joy.

One change that I will not forget that made the highest "perceived" impact with a one line change. The payments flow was at a different domain the rest of the site. This meant the users incurred a fresh set of DNS lookup, TCP connection establishment & a SSL handshake cost. The change was to load a "pixel" image from the payments domain a page before. It dropped the first call latency from 550ms to 100ms :-)