Degree of hyperbole admitted.
Would make my commute about 1.25 times longer. Would make the particular stretch of road on which there are 3 lights in 30 metres for no apparent reason take 100 times longer!
If I actually had to stop at every traffic light (i.e. if the consequences were worse than a bit of stick from some STW grumps), I wouldn’t bother cycling in at all. The whole thing would generally be sh1t, and in financial terms, the likely increased maintenance cost alone would make it uneconomic (i.e., brake pads and chain wear from all that stopping and starting).
I am overstating the case a bit but it’s the internet, that’s allowed.