Methods of processing lignocellulosic biomass to fermentable sugars are provided which rely on hydrothermal pretreatment. Soft lignocellulosic biomass feedstock is pretreated in a single-stage pressurized hydrothermal pretreatment to very low severity. The pre-treated biomass is hydrolysed, typically as a whole slurry, using enzymatic hydrolysis catalysed by an enzyme mixture comprising endoglucanase, exoglucanase, β-glucosidase, endoxylanase, and β-xylosidase activities at activity levels in nkat/g glucan of endoglucanase of at least 1100, exoglucanase of at least 280, β-glucosidase of at least 3000, endoxylanase of at least 1400, and β-xylosidase of at least 75, so as to produce a hydrolysate in which the yield of C5 monomers is at least 55% of the original xylose and arabinose content of the feedstock prior to pretreatment.