Completely agree that there are limited number of hours in the day and something will suffer. I do wonder whether a staged process is required eg just concentrate on basic numeracy and literacy skills in the first few years, nail it down, and then slowly bring a few more things in. I think IT doesn't need to be brought in until age 9-10 (ie year 5 & 6).
The French may study longer hours but don't they also start school later? No idea what they do in the pre-school years in terms of study. I'm wary of cramming in too much at a young age. That saying only really applies to adults and particularly the elderly, in whom it's proven that learning new things can help ward off dementia.