1. A method for processing data, comprising: accepting a specification of a plurality of patterns, each pattern defining a respective uncompressed sequence of symbols; and applying multi-pattern matching to an incoming stream of compressed communication traffic containing compression metadata so as to identify the patterns occurring in the stream while using the compression metadata to skip over parts of the stream, wherein the communication traffic is compressed by replacing recurring strings of the symbols with pointers to previous occurrences of the strings, and the compression metadata comprises the pointers, and wherein applying the multi-pattern matching comprises searching for the patterns among the symbols of the previous occurrences, and using the pointers to skip over at least a part of the recurring strings while processing the incoming stream, while assigning respective status indicators to the symbols in previous occurrences, and referring to the status indicators to identify the symbols to skip over in the recurring strings, wherein searching for the patterns comprises traversing a deterministic finite automaton (DFA) corresponding to the patterns, and wherein assigning the respective status indicators comprises determining respective depths of the symbols with respect to the DFA, and comparing the respective depths to a depth threshold in order to assign the status indicators.