The problem with tarts, and fruit tarts in particular, is that the filling (fruit, cream or whatever) ends up soaking into the pastry and turns it soft.
Here is a professional tip for avoiding this problem: spread a thin layer of white chocolate, which does not have a strong flavour, in the bottom of the tart. This seals the pastry and it will stay crisp.
French pastry chef have a verb for that, it's "chablonner".