This sounds like you may be getting some leaf-curl on your peach.
If so, then you will find the edges of the leaf will develop red blister like formations.
Pick the infected leaves off if these do develop and burn.
The problem often arises if the tree gets its young leaves wet in the spring and early summer months.
If your tree is against a wall or is a small bush then having some form of covour to protect it on wet days in the early season will help a lot.
Not practical though if the beastie is large.
Control otherwise is by a couple of methods that I know of.
A spray of Colloidal Copper wash at bud burst and Copper sulphate sprays ( Bordeaux Mixture ) in the early growing season helps enormously.