userid to ip mapping - F5 APM

I wouldn't be overly concerned about performance with this iRule, once every 10 seconds is not a lot but it depends on what else your system is doing. However there are things you can do to make your code more efficient.

For example, it's more expensive to set variables using the iRule namespace to make your code more readable. It's more efficient to execute the iRule commands when you need them:

if { [HTTP::uri] starts_with "/vdesk/timeoutagent-i.php" } {
     set removed - added directly to 'if'
    log local0. "timeout beacon received"
    if { [ACCESS::session data get "session.assigned.clientip"] != "" }{
    .
    .
    .. etc

Have a look here if you're interested in optimization:

https://devcentral.f5.com/articles/irules-optimization-101-05-evaluating-irule-performance

You could also configure a flag so that logging only happens when the flag is set so to avoid needless logging and computer resource