my imac continuous make pause and stop

i've a sequoia, with opencore 2.2 on a 3,4 ghz i5 nvidia kepler, with 16 gb ram.

i'use my mac , and all is ok, but every 5 minutes , it's pause, the cursor begin a round colorized circle, and lock position.

this also if i do lower app, or nothing .

after time continue work.

is stressing that , what's depending, ?

thanks in advance who help me.