Is this common(known) issue? When I configure one or two captures on the FTD(CLI or GUI) the device CPU increases by additional 20% even when the capture is full and Stopped/Paused.
I really did not saw any difference if I change the captures buffer size or any other capture option.
I noticed that when I talked to TAC a few weeks back to troubleshoot a FTD CPU issue - the first thing they did was to check if there were any captures on the FTD (back then it was a real CPU issue and no captures were present) they also noted that traffic captures can increase the CPU utilization.
But wen I was troubleshooting an issue today and placed a few captures on the interfaces I noised that the CPU spiked from 65% to 91%. After I removed the captures the CPU returned to normal (65%) for that time of the day - 8am(we have 4k RAVPN users on that FTD).