11. A computer system for optimizing generation of a regular expression utilized for entity extraction, the computer system comprising: one or more processors, one or more computer readable memories, one or more computer readable storage media, and program instructions stored on the one or more storage media for execution by the one or more processors via the one or more memories, the program instructions comprising: program instructions to receive, at a server, an input from a user of the server, the input enabling at least a first performance optimization parameter; program instructions to receive, from a user of a client computer, a query comprising a plain text word; program instructions to receive, at the server, data extracted from an electronic repository that is communicatively connected to the server, the data describing probabilities of spelling errors based, at least in part, on a number of syllables in the plain text word; program instructions to initialize, at the server, the first performance optimization parameter based, at least in part, on the received data and the input enabling at least the first performance optimization parameter; program instructions to optimize performance of generating a regular expression at the server, including program instructions to identify, using the first performance optimization parameter, a syllable within a plain text word that has a high probability of at least one of an incorrectly substituted and transposed character within a spelling of a word having a same number of syllables as the plain text word; program instructions to select, at the server, each character in the syllables identified; program instructions to identify, at the server, a group of characters from a confusion matrix that are commonly confused with the character selected; program instructions to generate, at the server, a set of characters for each character selected, wherein the set of characters begin with one of the each character selected followed by and ending with the group of characters from the confusion matrix; program instructions to generate, at the server, a regular expression by concatenating each set of characters; program instructions to, at the server, search, using the regular expression, the electronic repository for information relevant to the query; and program instructions to provide, to the user of the client computer, search results based on the regular expression.
13. The computer system of claim 11 , wherein the confusion matrix is implemented as a data structure.