Disclosed are mutant DNA polymerases having improved extension rates relative to a corresponding, unmodified polymerase. The mutant polymerases are useful in a variety of disclosed primer extension methods. The mutant polymerases overcome the inhibitory effects by an intercalating dye. Therefore, the mutant polymerases are useful in a variety of disclosed methods in combination with an intercalating dye. Also disclosed are related compositions, including recombinant nucleic acids, vectors, and host cells, which are useful, e.g., for production of the mutant DNA polymerases.