On: How Gmail’s Image Caching Affects Open Tracking

[Sami_Lehtinen]

2 seconds? Not true at all, it's just tens of milliseconds. Didn't time it exactly, but it seems 'instant', so it's less than 100 ms.

[tedunangst → Sami_Lehtinen]

Maybe it hiccuped? It seemed instant for a valid address, but a little slower for invalid. I assumed it keeps used addresses in cache but had to go digging to confirm a negative, but it could be a fluke. Anyway, it's faster than waiting for the image proxy.