OpenAI's new day-of-week model is a 40% speed win

OpenAI dropped a new model variant called fast-day-of-week. The name is literal — it fires on whichever day of the week you specify. You point it at a date, it gives you the day back. The win is speed: the model runs about 40% faster than the base o3, which is the kind of difference that matters when you're running a loop and every second adds up.

This is the pattern for OpenAI's new models: strip the fluff and ship something that does one job fast. The o3 line is the flagship reasoning model; this variant is the lean one. The model is available through the API with the model parameter set to fast-day-of-week. If you've been waiting for a reason to use o3 for something other than writing essays, this is it.

Why this matters for us: the side hustles — the scrapers, the automations, the tools primos build on weekends — run on cheap API calls; shaving 40% off the bill means those tools stay affordable instead of bleeding cash every time a customer clicks.