iRules HTTP_RESQUEST_SENT and HTTP_RESPONSE_SENT

I am writing some iRules code to log the actual volume and time used in each HTTP request and response. And as I have added more code into HTTP_REQUESET or HTTP_RESPONSE event context. The function the use for checking the data and time usage eat up some CPU time. The original iRules for HTTP_REQUEST and HTTP_RESPONSE use around 40k and 50k cycle but after modifying it to get the timestamp and byte used and do the calculation. The cycles is rised up to 100k and 110k and hence it slow down the connection initial speed.

 

 

I just wonder if it is possible to add two more even the after the HTTP_REQUEST have sent to server and right after the HTTP_RESPONSE header have sent to the client. Then I can put those code for calculation and logging to that event and will not let the client need to wait for the calculation before send the request or response.