Did you learn to read Polish or English at that age? As someone whose first language is written as it is spoken, I believe that reading English for English kids is much-much-much harder. Reading in a language with a letter-sound correspondence is entirely trivial. You speak that language, you learn the characters, you're done. Reading English requires to learn an entirely new language, hundreds of words. (Especially if reading English is taught simultaneously with writing English--I don't know about that.)

I can't find any real studies about this subject with numbers; how much effort does it take for an Italian/Spanish/Finnish/Polish/.. kid to learn to read vs for English kids. Or, for example how many of them are able to 'teach themselves' to read just by looking at the picture books, and asking parents about letters.