I have a Spirent C1 chasis. I am using Spirent TestCenter's Command Sequencer with Iterate Load Size command to generate a traffic that changes with time. It was suggested in the forum at https://forums.spirent.com/questions/35855/how-to-generate-a-traffic-whose-rate-changes-with.html . I have 20 traffic sources (streamblocks) generating traffic at different rates. For each traffic source there is a different "iterate load size" command whose load values are set in "custom load list" variable. When I do a single loop, it takes around 15 seconds to process 20 "iterate load size" commands in each loop. Therefore, the traffic rate of each source becomes constant for 15 seconds until its "iterate load size" command is processed in the next loop. Is there are way to increase the speed of this loop to generate traffic that changes more frequently? I tried TCL API without using the GUI, but there was no speed improvement.