1. A method for load testing a server comprising: executing a client application on a client device, wherein a client callback object is used by the client application in a transaction between the server and the client device; capturing the transaction with a recorder; filtering internal client operations from the client callback object to create a virtual callback object; generating a script, using the virtual callback object; and executing the script on a plurality of virtual clients in the client device, wherein executing the script comprises pausing a thread of the script when the virtual callback object is used until all desired responses to the virtual callback object are received from the server, wherein the thread emulates one or more of the virtual clients.