can you do a traceroute and see where the latency is being introduced? also a good check is to look at CPU and Memory levels since if they are choking you are limiting resources for control plane. 

Hello, Are you talking about RSPAN or Local SPAN? Check this config guide for the same:  https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9200/software/release/16-9/configuration_guide/nmgmt/b_169_nmgmt_9200_cg/configuring_span_and_rspan.ht...

your SUP is eol/eos : https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/eol_c51-697975.html   you will not find IOS for the same.   ## Make sure to mark post as helpful, If it resolved your issue. ##

RMA the switch POST is failing :   POST: PortASIC Port Loopback Tests : BeginPOST: Failed PortPhyLoopback Packet Test asic_index 0 port_hardware_index 23POST: PortASIC Port Loopback Tests : End, Status Failed       ## Make sure to mark post as helpfu...