1. A computer-implemented method for efficiently parsing received data files, comprising: receiving, by a virtual browser executing on a server that is intermediary to a plurality of clients and a plurality of web servers, a data file from one of the plurality of web servers, responsive to a request by one of the plurality of clients; determining that the received data file comprises an object that is not cached on the server; determining whether the object is currently being tracked; retrieving a previously stored version of the data file and a syntax tree comprising nodes and tokens representing data within the previously stored version of the data file, the syntax tree including at least one static node; comparing the previously stored version of the data file with the received data file and identifying non-matching content in the received data file; parsing only the non-matching content of the received data file; updating the syntax tree by replacing the at least one static node of the syntax tree with a new token; creating a mapping from the new token to a subtree in the syntax tree; and storing the updated syntax tree.
1. A computer-implemented method for efficiently parsing received data files, comprising: receiving, by a virtual browser executing on a server that is intermediary to a plurality of clients and a plurality of web servers, a data file from one of the plurality of web servers, responsive to a request by one of the plurality of clients; determining that the received data file comprises an object that is not cached on the server; determining whether the object is currently being tracked; retrieving a previously stored version of the data file and a syntax tree comprising nodes and tokens representing data within the previously stored version of the data file, the syntax tree including at least one static node; comparing the previously stored version of the data file with the received data file and identifying non-matching content in the received data file; parsing only the non-matching content of the received data file; updating the syntax tree by replacing the at least one static node of the syntax tree with a new token; creating a mapping from the new token to a subtree in the syntax tree; and storing the updated syntax tree. 3. The computer-implemented method of claim 1 wherein the data file is an HTML file.