high cpu

[AK]

OS :hp-ux oracle rdbms 8.1.7.4   there are certain processes taking lot of cpu ( some thing went wrong with stastics last nite). which is causing almost a halt in production database.these processes are killed from oracle but i can still see them on OS .Cpu is still high . I though after killing them mpon might be doing some clean up work .cpu is still high .   question : If I recycle this instance ,is it going to take long time to come back . ( smon will do the job now ?) or is "fast warm start" will help here to bring db up quickly?   thanks, -Ak