Buy a litre of Motul 600 off eBay for about £16 and bleed the whole system. It is pretty common that you have to double tap the brakes to get the best from them, but it's how much of a difference that matters.
If it's like night and day then get the fluid and sort it, but be sure to bleed them in the correct order which I think is NSR, OSF, OSR, NSF and always the inner bleed nipple first as there is 2 on each caliper.