RB High CPU usage with IPSEC

I have three RB (rb750gl, rb1100ahx2,etc) with 5.26 firmware. all are working at different sites as a simple router configured as pppoe+hotspot server for lan users. all of them are having strange issue of HIGH cpu usage and in profile, it shows that IPSEC is chocking the CPU. there is no vpn or nay kind of setup in these rb. please see the attached image…

ipsec-cpu-high-usage.png