1. A method comprising: accessing transaction data generated during monitoring of a plurality of transactions involving a plurality of software components in a system; determining, from the transaction data, a flow of a particular one of the plurality of transactions, wherein the flow of the particular transaction describes involvement of a particular set of the plurality of software components in the particular transaction and a plurality of transaction fragments of the particular transaction; determining a duration of each of the plurality of transaction fragments; determining a relative duration of a particular one of the plurality of transaction fragments based on the duration of the particular transaction fragment, wherein the relative duration is relative to a duration of another instance of the particular transaction fragment in another transaction previous to the particular transaction; and generating a graphical representation of the flow for presentation in a graphical user interface, wherein the graphical representation comprises a set of graphical block elements and a set of graphical connector elements, each of the graphical block elements representing a respective one of the plurality of software components, each of the graphical connector elements representing a respective one of the plurality of transaction fragments and connecting the graphical block elements of the respective software components involved in the corresponding transaction fragment, and a particular one of the graphical connector elements representing the particular transaction is formatted to indicate the relative duration determined for the particular transaction fragment.