Ksoftirqd high CPU usage

my router is Xiaomi Router 3G v1
when it was on openwrt 19.07, almost everything fine, at least the network is fast.
when i had flashed 21.02, i have got many times of ksoftirqd high cpu usage notifition, and the network became very slow. i thought it would be fixed in the new version and i kept update to the last versions, but till now the issue still here. i searched on internet something about ksoftirqd but i still how to fixed it. here is some infomation may be helpful.

$ cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3       
  8:  177891371  177891360  177891430  177891406  MIPS GIC Local   1  timer
  9:   25820525          0          0          0  MIPS GIC  63  IPI call
 10:          0   32282436          0          0  MIPS GIC  64  IPI call
 11:          0          0   40719383          0  MIPS GIC  65  IPI call
 12:          0          0          0   31543117  MIPS GIC  66  IPI call
 13:  113883032          0          0          0  MIPS GIC  67  IPI resched
 14:          0  128889050          0          0  MIPS GIC  68  IPI resched
 15:          0          0   36985722          0  MIPS GIC  69  IPI resched
 16:          0          0          0   65349319  MIPS GIC  70  IPI resched
 17:          0          0          0          0  MIPS GIC  19  1e000600.gpio-bank0, 1e000600.gpio-ba
 19:         12          0          0          0  MIPS GIC  33  ttyS0
 20:    6566257          0          0          0  MIPS GIC  29  xhci-hcd:usb1
 21:  167918023          0          0          0  MIPS GIC  10  1e100000.ethernet
 23:      16696          0  189573464          0  MIPS GIC  11  mt7603e
 24:       3187          0          0   92990258  MIPS GIC  31  mt76x2e
 26:          0          0          0          0  1e000600.gpio  18  keys
ERR:      52852

how could i get some help from openwrt offical developers?