I recently changed my gpt-o4-mini to gpt-5-nano and later tested all other gpt5 models, only to find that all of them are at least 10x slower! Honestly anything gpt5 just sucks completely!
I understand in case there’s some internal routing done but some transparency should be in place. It’s (gpt5 that is) communicated as the fastest replacement for the 4 series but that is simply not the truth.
Am I’m the only one finding this. Our customer’s were not excited about the lack of performance. In addition model performance fluctuates a lot - from bad to worth.