Apple Crumble doesn't turn out okay and takes forever
It took more than an hour and a half for the top to begin to brown


I take away that this is what you are looking for as a sign of done-ness, but when you get it the rest of the thing is overcooked.  

You can get the top to brown faster either by adding some extra sugar to the top (sprinkle it on) or toasting it under the broiler for a minute or two once the rest has baked.  

It is also possible your oven is miscalibrated.  Maybe it is cooler than you think.   Bake an oven thermometer and see if it agrees with the temperature you think your oven is set at.