Of the major types of chocolate, white chocolate typically melts the fastest. Milk chocolate usually melts slower than white chocolate, but faster than semi-sweet chocolate or dark chocolate. In most cases, dark chocolate has the slowest melting speed.
White chocolate tends to have a faster melting speed than other types because it primarily consists of heat-sensitive cocoa butter rather than pure cocoa. Generally, higher cocoa content within chocolate will result in increased melting times. This is why the cocoa-heavy dark chocolate takes the longest amount of time to melt.
Certain factors may impact the speed and efficiency of melting chocolate. According to the Better Homes & Gardens website, the chocolate should be divided into even, same-sized pieces in order to improve melting.