Hi,
Try recreating the issue while XPI Inspector is started.
Looks like the system is unable to handle the spike in volume and resulting in many request wait until timeout.
Try increasing max number of threads (icm/max_threads) and timeout for http service (icm/server_port_0 = PROT=HTTP,PORT=5$(SAPSYSTEM)00,TIMEOUT=1800,PROCTIMEOUT=16000) in ICM.
Increase XMBWS.Timeout value in the Communication Channel.
regards
AKD