The idea that all starches will digest much slower than table sugar, due to the length of its chain, has been shown to be incorrect. The speed is actually due to the types of links between the simple sugars; each type of link usually needs a separate type of enzyme to break it, and the link being broken does not need to be at the end of the chain. Humans don't have the type of enzyme needed to break the links found in cellulose, which makes cellulose a fiber that humans cannot digest. Cellulose is one of the main ingredients in wood.
Some of the foods with carbs that digest slowly are sweet potatoes, cooked dried beans, and pizza.
You can add maize (known as corn here in the US) to the list of high-carb foods.