The CPUs may appear to be very busy. There may be one or two or many cpus which are very busy. Some may be 100% busy at all times. The system has some CPUs which are dedicated to processes. Complex reports or extractions will use multiple CPUs. Reports and extractions with wide timespans may require one or more CPUs for extended periods of time.
Each criteria specified will cause a search to determine if there is a match. If there are three search criteria, there will be three searches. Each search will extend the amount of time that a report will run and the amount of time a CPU is consumed. Try to reduce the number of criteria to what is needed or expect more CPU time required to complete a report.