March 18, 2026 · Cloudflare
Rules - Worker execution timing field now available in Rules
The cf.timings.worker_msec field is now available in the Ruleset Engine. This field reports the wall-clock time that a Cloudflare Worker spent handling a request, measured in milliseconds.
You can use this field to identify slow Worker executions, detect performance regressions, or build rules that respond differently based on Worker processing time, such as logging requests that exceed a latency threshold.
Field details
Field Type Descriptioncf.timings.worker_msec
Integer
The time spent executing a Cloudflare Worker in milliseconds. Returns 0 if no Worker was invoked.
Example filter expression:
cf.timings.worker_msec > 500
For more information, refer to the Fields reference.