It really depends on the software, I have the obsqr app (based on a native library) on a 600Mhz android phone from 2010 and I get recognition in probably less t

It really depends on the software, I have the obsqr app (based on a native library) on a 600Mhz android phone from 2010 and I get recognition in probably less than 0.5 seconds after pointing it at the code. Meanwhile the whatsapp web code reader on the same device and same qr code takes more than 6 seconds of careful aligning, and even on modern devices there are still some hilariously bad code readers (having to manually align the corner squares with an overlay)